add channel ID, expand readme

main.py

@@ -24,6 +24,7 @@ def main():
         config.PEERTUBE_HOST = os.environ['PEERTUBE_HOST'].rstrip('/')
         config.PEERTUBE_USER = os.environ['PEERTUBE_USER']
         config.PEERTUBE_PASS = os.environ['PEERTUBE_PASS']
+        config.PEERTUBE_CHANNEL_ID = os.environment['PEERTUBE_CHANNEL_ID']
     except KeyError as e:
         print(
             f'Error: PeerTube host and credentials must be specified: {e}', file=sys.stderr)