Added new boads pinout images for ESP32, ESP32-S2 and ESP32-C3 (espressif#5133)

Board images updated and added warning on Flash/PSRAM pins

Author: pedrominatel

Diff for: README.md

@@ -50,6 +50,8 @@ Finally, if you are sure no one else had the issue, follow the [ISSUE_TEMPLATE](
 
 ![ESP32S2_Pinmap](docs/esp32s2_pinmap.png)
 
+![ESP32C3_Pinmap](docs/esp32c3_pinmap.png)
+
 ### Tip
 
 Sometimes to program ESP32 via serial you must keep GPIO0 LOW during the programming process