STT: Add docs for offline STT on Android

plyer/facades/speech.py

@@ -1,5 +1,7 @@
 class Speech(object):
     '''
+    .. versionadded:: 1.3.3
+
     Speech Recognition facade.
 
     In order to check that your device supports voice recognition use method
@@ -11,7 +13,7 @@ class Speech(object):
     Use `start` to start voice recognition immediately and `stop` to stop.
 
     .. note::
-        Needed permissions for Android: `RECORD_AUDIO` (and `NETWORK` if you
+        Needed permissions for Android: `RECORD_AUDIO` (and `INTERNET` if you
         want online voice recognition API to be used)
 
     .. note::
@@ -23,6 +25,28 @@ class Speech(object):
         with `android.speech.RecognitionService` implementation present
         in the system. Mostly it's `com.google.android.googlequicksearchbox`
         or "Google" application (the search bar with the launcher widget).
+
+    Offline Speech Recognition on Android
+    -------------------------------------
+
+    Requires any application that provides an
+    `android.speech.RecognitionService` implementation to the other apps. One
+    of such applications is on a lot of devices preinstalled Google (quick
+    search box).
+
+    The API prefers offline recognition, but should be able to switch to online
+    alternative in case you don't have a language package installed (`INTERNET`
+    permission necessary).
+
+    You can enable offline speech recognition this way (Android 8.1):
+
+    * open the `Settings` app
+    * choose `Language & Input` / `Language & Keyboard` (Samsung might include
+      it in the `General` category)
+    * choose `On-Screen keyboard` or `Voice search`
+    * choose `Google Keyboard`
+    * choose `Offline Speech recognition`
+    * download language package if you don't have one already
     '''
 
     _language = 'en-US'