[99s-extend] sub_description is not a valid app configuration option

[Grzegorz Junka]

Hi,
I am trying to compile a release with some applications for which ranch 
and cowboy are dependencies. This is what I am getting on the console:

reltool: Unexpected item sub_description in app file 
"/usr/home/somepath/deps/ranch/ebin/ranch.app".
reltool: Unexpected item sub_description in app file 
"/usr/home/somepath/deps/cowboy/ebin/cowboy.app".

When looking it up on Erlang documentation it seems that sub_description 
is not a valid configuration options in the .app file. Is there any 
chance to put it rather as a comment?