docs: standardize download

src/Download/README.md

@@ -1,22 +1,19 @@
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+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements.  See the NOTICE file
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+* distributed under the License is distributed on an "AS IS" BASIS,
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 # Release version
@@ -233,7 +230,7 @@ Legacy version are available here: [https://archive.apache.org/dist/iotdb/](http
 
   - Set the somaxconn as 65535 to avoid "connection reset" error when the system is under high load.
 
-    ```
+    ```bash
     # Linux
     > sudo sysctl -w net.core.somaxconn=65535
 
@@ -264,7 +261,7 @@ In previous versions of syntax conventions, when do you need to add quotation ma
 
 In previous versions of syntax conventions, path node names were defined as identifiers, but when the path separator . was required in the path node name, single or double quotes were required. This goes against the rule that identifiers are quoted using backquotes.
 
-```SQL
+```sql
 # In the previous syntax convention, if you need to create a time series root.sg.`www.baidu.com`, you need to use the following statement:
 create root.sg.'www.baidu.com' with datatype=BOOLEAN, encoding=PLAIN
 
@@ -276,7 +273,7 @@ select 'www.baidu.com' from root.sg;
 
 **In the 1.0 syntax conventions, special node names are uniformly quoted using backquotes:**
 
-```SQL
+```sql
 # In the new syntax convention, if you need to create a time series root.sg.`www.baidu.com`, the syntax is as follows:
 create root.sg.`www.baidu.com` with 'datatype' = 'BOOLEAN', 'encoding' = 'PLAIN'
 
@@ -288,7 +285,7 @@ select `www.baidu.com` from root.sg;
 
 In previous versions of syntax conventions, when single quotes ' and double quotes " are used in path node names, they need to be escaped with a backslash \, and the backslashes will be stored as part of the path node name. Other identifiers do not have this restriction, causing inconsistency.
 
-```SQL
+```sql
 # Create time series root.sg.\"a
 create timeseries root.sg.`\"a` with datatype=TEXT,encoding=PLAIN;
 
@@ -356,7 +353,7 @@ Query the data of root.sg.a, you can see that there is no unescaping:
 
 Instead use SQL to insert data into root.sg.a:
 
-```SQL
+```sql
 # SQL insert
 insert into root.sg(time, a) values(1, "\\")
 insert into root.sg(time, a) values(2, "\t")
@@ -391,27 +388,27 @@ Query the data of root.sg.a, you can see that the string is unescaped:
 
   - The data format (i.e., TsFile data) of v0.12.x and v0.13.x are compatible, but the WAL file is
     incompatible. So, you can follow the steps:
-  - **<font color=red> Execute `SET SYSTEM TO READONLY` command in CLI. </font>**
-  - **<font color=red> Stop writing new data.</font>**
+  - **<span style="color:red"> Execute `SET SYSTEM TO READONLY` command in CLI. </span>**
+  - **<span style="color:red"> Stop writing new data.</span>**
   - Execute `flush` command to close all TsFiles.
   - We recommend to back up all data files before upgrading for rolling back.
-  - Just download, unzip v0.13.x.zip, and modify conf/iotdb-engine.properties, **<font color=red> especially the unchangeable configurations like timestamp precision</font>**. Let all the
+  - Just download, unzip v0.13.x.zip, and modify conf/iotdb-engine.properties, **<span style="color:red"> especially the unchangeable configurations like timestamp precision</span>**. Let all the
     directories point to the data folder set in v0.12.x (or the backup folder). You can also modify
     other settings if you want.
   - Stop IoTDB v0.12.x instance, and then start v0.13.x.
-  - **<font color=red>After the steps above, please make sure the `iotdb_version` in `data/system/schema/system.properties` file is `0.13.x`.
-    If not, please change it to `0.13.x` manually.</font>**
+  - **<span style="color:red">After the steps above, please make sure the `iotdb_version` in `data/system/schema/system.properties` file is `0.13.x`.
+    If not, please change it to `0.13.x` manually.</span>**
   - **NOTICE: V0.13 changes many settings in conf/iotdb-engine.properties, so do not use v0.12's
     configuration file directly.**
   - **In 0.13, the SQL syntax has been changed. The identifiers not enclosed in backquotes can only contain the following characters, otherwise they need to be enclosed in backquotes.**
-    - **[0-9 a-z A-Z _ : @ # $ { }] (letters, digits, some special characters)**
-    - **['\u2E80'..'\u9FFF'] (UNICODE Chinese characters)**
+    - **\[0-9 a-z A-Z _ : @ # $ { }] (letters, digits, some special characters)**
+    - **\['\u2E80'..'\u9FFF'] (UNICODE Chinese characters)**
   - **In 0.13, if the path node name in the `SELECT` clause consists of pure numbers, it needs to be enclosed in backquotes to distinguish it from the constant in the expression. For example, in the statement "select 123 + \`123\` from root.sg", the former 123 represents a constant, and the latter \`123\` will be spliced with root.sg, indicating the path root.sg.\`123\`.**
 
 - How to upgrade from v0.11.x or v0.10.x to v0.12.x?
 
   - Upgrading from v0.11 or v0.10 to v0.12 is similar as v0.9 to v0.10. The upgrade tool will rewrite the data files automatically.
-  - **<font color=red>Stop writing new data.</font>**
+  - **<span style="color:red">Stop writing new data.</span>**
   - Call `flush` command using sbin/start-cli.sh in original version to close all TsFiles.
   - We recommend to backup the data file (also the wal files and mlog.txt) before upgrading for rolling back.
   - Just download, unzip v0.12.x.zip, and modify conf/iotdb-engine.proeprties to let all the
@@ -428,7 +425,7 @@ Query the data of root.sg.a, you can see that the string is unescaped:
 
   - The data format (i.e., TsFile data) of v0.10.x and v0.11 are compatible, but the WAL file is
     incompatible. So, you can follow the steps:
-  - **<font color=red>Stop writing new data.</font>**
+  - **<span style="color:red">Stop writing new data.</span>**
   - Call `flush` command using `sbin/start-cli.sh` in v0.10.x to close all TsFiles.
   - We recommend to backup the wal files and mlog.txt before upgrading for rolling back.
   - Just download, unzip v0.11.x.zip, and modify conf/iotdb-engine.properties to let all the
@@ -442,7 +439,7 @@ Query the data of root.sg.a, you can see that the string is unescaped:
 - How to upgrade from v0.9.x to v0.10.x?
 
   - Upgrading from v0.9 to v0.10 is more complex than v0.8 to v0.9.
-  - **<font color=red>Stop writing new data.</font>**
+  - **<span style="color:red">Stop writing new data.</span>**
   - Call `flush` command using sbin/start-client.sh in v0.9 to close all TsFiles.
   - We recommend to backup the data file (also the wal files and mlog.txt) before upgrading for rolling back.
   - Just download, unzip v0.10.x.zip, and modify conf/iotdb-engine.proeprties to let all the
@@ -465,4 +462,4 @@ Find all releases in the [Archive repository](https://archive.apache.org/dist/io
 
 # Verifying Hashes and Signatures
 
-Along with our releases, we also provide sha512 hashes in _.sha512 files and cryptographic signatures in _.asc files. The Apache Software Foundation has an extensive tutorial to [verify hashes and signatures ](http://www.apache.org/info/verification.html)which you can follow by using any of these release-signing [KEYS ](https://downloads.apache.org/iotdb/KEYS).
+Along with our releases, we also provide sha512 hashes in _.sha512 files and cryptographic signatures in `_.asc` files. The Apache Software Foundation has an extensive tutorial to [verify hashes and signatures](http://www.apache.org/info/verification.html)which you can follow by using any of these release-signing [KEYS](https://downloads.apache.org/iotdb/KEYS).