Add nginx comment for webseed redirection

support/nginx/peertube

@@ -247,6 +247,7 @@ server {
     sendfile_max_chunk 1M; # prevent one fast connection from entirely occupying the worker process. should be > 800k.
     aio threads;
 
+    # web-videos is the name of the directory mapped to the `storage.web_videos` key in your PeerTube configuration
     rewrite ^/static/webseed/(.*)$ /web-videos/$1 break;
     rewrite ^/static/(.*)$         /$1        break;