Add onfo on this doc and its overview status

Reference *CONTRIBUTING.md* and *S26* as the primary sources of this info.

doc/Language/about.pod6

@@ -15,10 +15,15 @@ L<https://docs.perl6.org>.
 The official source for this documentation is located at L<perl6/doc on
 GitHub|https://github.com/perl6/doc>.
 
+The information in this document is a quick overview of the process
+described in more detail in L<CONTRIBUTING on GitHub|https://github.com/perl6/doc/CONTRIBUTING.md>.
+This document also provides a short introduction ot writing the Perl 6
+POD files which produce these web pages.
+
 =head1 Structure
 
-All of the documentation is written in Pod6 and kept in the C<lib/>
-directory, and the C<lib/Language/> and C<lib/Type/> sub-directories.
+All of the documentation is written in Pod6 and kept in the C<doc/>
+directory, and the C<doc/Language/> and C<doc/Type/> sub-directories.
 These files are processed as collections of definitions or
 "documentables", which are then post-processed and linked together.