app: make main() in west.app.main module public API

Added documentation to main() as it is now officially supported to
directly call main from west.app.main module.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

src/west/app/main.py

@@ -8,7 +8,7 @@
 
 '''Zephyr RTOS meta-tool (west) main module
 
-Nothing in here is public API.
+Only the main() method in here is public API.
 '''
 
 import argparse
@@ -754,6 +754,14 @@ def dump_traceback():
     return name
 
 def main(argv=None):
+    '''Run the application with argument list ``argv``.
+
+    The argument list is identical to the command-line west application
+    arguments, see ``west help``
+
+    :param argv: argument list, the list of valid arguments can be seen by
+        invoking ``west help``
+    '''
     # Silence validation errors from pykwalify, which are logged at
     # logging.ERROR level. We want to handle those ourselves as
     # needed.