docs: more precise description of supported devices (tobiasschuerg#135)

CHANGELOG.md

@@ -10,6 +10,9 @@
  - [#156](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/156) - Correctly rounding _writeBufferSize_, when _bufferSize/batchSize >= 256_. 
  - [#162](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/162) - Fixed flushing of not full buffer after the flush timeout.
 
+ ### Documentation
+ - [#163](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/163) - More precise description of supported devices
+
 ## 3.8.0 [2021-04-01]
 ### Features
  - [#143](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/143) - `InfluxDBClient::setInsecure` now works also for ESP32. Requires Arduino ESP32 SDK 1.0.5 or higher

README.md

@@ -8,8 +8,13 @@ Library supports both [InfluxDB 2](#basic-code-for-influxdb-2) and [InfluxDB 1](
 
 This is a new implementation and the API, [original API](#original-api) is still supported.
 
-Supported devices: ESP8266 (2.7+) and ESP32 (1.0.3+).
+Supported devices: 
+ - ESP8266 with [Arduino core for ESP8266](https://github.com/esp8266/Arduino) at least version [2.7.4](https://github.com/esp8266/Arduino/releases/tag/2.7.4). Version [3.0.2](https://github.com/esp8266/Arduino/releases/tag/3.0.2) is recommended.
+ - ESP32 with [Arduino core for the ESP32](https://github.com/espressif/arduino-esp32) at least version [1.0.3](https://github.com/espressif/arduino-esp32/releases/tag/1.0.3). Version [2.0.0](https://github.com/espressif/arduino-esp32/releases/tag/2.0.0) is recommended.
 
+This library doesn't support using those devices as a peripheral.
+
+## Table of contents
 - [InfluxDB Arduino Client](#influxdb-arduino-client)
   - [Basic code for InfluxDB 2](#basic-code-for-influxdb-2)
   - [Basic code for InfluxDB 1](#basic-code-for-influxdb-1)