update readme

README.md

@@ -1,14 +1,46 @@
 # elastic-tools
-CLI Utilities to export/import JSON from elasticsearch
 
+CLI Utilities to export/import JSON from elasticsearch
 
 ## Usage
+
 ### Exporting data to json
+
 ```bash
 elastic-export --host 127.0.0.1:9200 --index MyIndex --out ./data.json
 ```
 
+The \_id of the document from elastic's index will be part of the body of the exported document: 
+
+For example, this document from elastic:
+
+```json
+{
+  "_index": "users",
+  "_type": "_doc",
+  "_id": "1",
+  "_score": 1,
+  "_source": {
+    "active": true,
+    "name": "User 1",
+    "email": "email1"
+  }
+}
+```
+will be exported to JSON like this:
+
+```json
+{
+  "_id": "1",
+  "active": true,
+  "name": "User 1",
+  "email": "email1"
+}
+```
+
+
 ### Importing data from json array
+
 ```bash
 elastic-import --host 127.0.0.1:9200 --index MyIndex --data ./data.json
-```
+```