fix issue links

README.md

@@ -20,8 +20,8 @@ supports other models:
  Model                  | Define [^1]  | Notes
  ---------------------- |:------------ |:---------------------------------------------------
  Intex PureSpa SB-H20   | MODEL_SB_H20 | supported
- Intex SimpleSpa SB–B20 | MODEL_SB_H20 | reported to be compatible, see [issue #5](issues/5)
- Intex PureSpa SJB-HS   | MODEL_SJB_HS | supported, see [issue #13](issues/13)
+ Intex SimpleSpa SB–B20 | MODEL_SB_H20 | reported to be compatible, see [issue #5](../../issues/5)
+ Intex PureSpa SJB-HS   | MODEL_SJB_HS | supported, see [issue #13](../../issues/13)
  Intex PureSpa SSP-H    | MODEL_SJB_HS | not tested [^2]
 
 [^1]: #define required for build (see common.h)
@@ -38,9 +38,9 @@ WiFi remote control using the [MQTT](https://mqtt.org/) protocol.
 This is no ready-to-use product. The acquisition of the required hardware
 components, their assembly and programming requires some experience with DIY
  electronics. Helpful details can also be found in the
-[issues](issues) of this project
+[issues](../../issues) of this project
 (e.g. a table of the hardware components not shown in the schematic can be
-found in [issue #2](issues/2)).
+found in [issue #2](../../issues/2)).
 
 > :warning: **WARNING**: If you decide to implement the presented solution
   you will void the warranty of your pool as it requires invasive
@@ -218,8 +218,8 @@ The following **components** are required to build the firmware:
 
  Component    | Version | Notes
  ------------ |:------- |:-------------------------------------------------------------------------------------------------------
- Arduino IDE  | 1.8     | firmware does not build successfully with 2.X, see [issue #30](issues/30)
- ESP8266 SDK  | 2.7.4   | install using the Arduino board manager,<br/>3.1.2 is also reported to work, see [issue #13](issues/13)
+ Arduino IDE  | 1.8     | firmware does not build successfully with 2.X, see [issue #30](../../issues/30)
+ ESP8266 SDK  | 2.7.4   | install using the Arduino board manager,<br/>3.1.2 is also reported to work, see [issue #13](../../issues/13)
  ArduinoJSON  | 6.19.4  | install using the Arduino library manager
  PubSubClient | 2.8     | install using the Arduino library manager