remove redundant webclient configs

These just emit warnings, as of #4290

debian/homeserver.yaml

@@ -70,13 +70,9 @@ pid_file: "/var/run/matrix-synapse.pid"
 #
 # cpu_affinity: 0xFFFFFFFF
 
-# Whether to serve a web client from the HTTP/HTTPS root resource.
-web_client: False
-
-# The root directory to server for the above web client.
-# If left undefined, synapse will serve the matrix-angular-sdk web client.
-# Make sure matrix-angular-sdk is installed with pip if web_client is True
-# and web_client_location is undefined
+# The path to the web client which will be served at /_matrix/client/
+# if 'webclient' is configured under the 'listeners' configuration.
+#
 # web_client_location: "/path/to/web/root"
 
 # The public-facing base URL for the client API (not including _matrix/...)