Check if readme file is empty or not

[kafleg]

Theme with empty readme file can be blocked.
https://themes.svn.wordpress.org/ynet-contractor/1.0/

This theme ticket has that issue. Readme file is empty. Currently, only readme files that exist or not will check.

[kafleg]

I see a similar issue in another theme as well, https://themes.svn.wordpress.org/eduthemealulu/4.0/readme.txt