add docs for dotenv BLE

Author: Neradoc

docs/environment.rst

@@ -31,9 +31,17 @@ CircuitPython behavior
 CircuitPython will also read the environment to configure its behavior. Other
 keys are ignored by CircuitPython. Here are the keys it uses:
 
+CIRCUITPY_BLE_NAME
+~~~~~~~~~~~~~~~~~~
+Default BLE name the board advertises as, including for the BLE workflow.
+
+CIRCUITPY_WEB_API_PASSWORD
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+Password required to make modifications to the board from the Web Workflow.
+
 CIRCUITPY_WIFI_PASSWORD
 ~~~~~~~~~~~~~~~~~~~~~~~
-Wi-Fi password used to auto connect to CIRCUITPY_WIFI_SSID
+Wi-Fi password used to auto connect to CIRCUITPY_WIFI_SSID.
 
 CIRCUITPY_WIFI_SSID
 ~~~~~~~~~~~~~~~~~~~

docs/workflows.md

@@ -45,6 +45,10 @@ using a rotating key rather than a static one. Non-bonded devices won't be able
 connection, the central device can discover two default services. One for file transfer and one for
 CircuitPython specifically that includes serial characteristics.
 
+To change the default BLE advertising name without (or before) running user code, the desired name
+can be put in the `/.env` file. The key is `CIRCUITPY_BLE_NAME`. It's limited to approximately
+30 characters depending on the port's settings and will be truncated if longer.
+
 ### File Transfer API
 
 CircuitPython uses [an open File Transfer API](https://github.com/adafruit/Adafruit_CircuitPython_BLE_File_Transfer)