Log Message:
textproc/ruby-rdiscount: update to 2.2.7

pkgsrc change: switch to use RUBYGEM_MANPAGES.

2.2.7 (2022-10-23)

* Discount upgraded from 2.2.0 -> 2.2.7c
	- Implement support for :latex
	- Implement support for :explicitlist
* Move CI to GitHub action and fix CI builds (Ruby 2.7 - 3.1)
* Drop support for all EOL Ruby versions (eg > 2.7)
* Fixing conformance tests to run version 1.0 and 1.0.3