Make wporg_filter_archive_title() more versatile

* Don't apply in admin
* Don't apply if post isn't passed in
Add and use get_long_description() to get parsed long descriptions from meta
Add 'Explanation' section to parsed content pages (if present)

Explanations are stored as post_content.
Display only the major version (X.Y) of the release in the header for the "New in" section
Temporary fix to format the display of params defined using hash notation.