main: enable TAG_{KIND,EXTRA,FIELD,ROLE}_DESCRIPTION pseudo tags

[masatake]

    https://github.com/universal-ctags/ctags/pull/2741/commits/e5d7cedc9e41aa734dda2d8b60f49ce73bd02db5 must be included in ctags6.

Originally posted by @masatake in #2741 (comment)