cosmetics

- fix typo
- fix spaces
- full sentence

docs/nginx/dendrite-sample.conf

@@ -20,8 +20,9 @@ server {
     }
 
     location /.well-known/matrix/client {
-        # If your sever_name here doesn't match your matrix homeserver URL
+        # If your server_name here doesn't match your matrix homeserver URL
         # (e.g. hostname.com as server_name and matrix.hostname.com as homeserver URL)
+        # uncomment the following line.
         # add_header Access-Control-Allow-Origin '*';
         return 200 '{ "m.homeserver": { "base_url": "https://my.hostname.com" } }';
     }