[README.md] Add comments in sample configuration for clarity

README.md

@@ -412,11 +412,19 @@ You can configure youtube-dl by placing any supported command line option to a c
 
 For example, with the following configuration file youtube-dl will always extract the audio, not copy the mtime, use a proxy and save all videos under `Movies` directory in your home directory:
 ```
--x
---no-mtime
---proxy 127.0.0.1:3128
--o ~/Movies/%(title)s.%(ext)s
 # Lines starting with # are comments
+
+# Always extract audio
+-x
+
+# Do not copy the mtime
+--no-mtime
+
+# Use this proxy
+--proxy 127.0.0.1:3128
+
+# Save all videos under Movies directory in your home directory
+-o ~/Movies/%(title)s.%(ext)s
 ```
 
 Note that options in configuration file are just the same options aka switches used in regular command line calls thus there **must be no whitespace** after `-` or `--`, e.g. `-o` or `--proxy` but not `- o` or `-- proxy`.