Adding a comment about using a typed pattern in 'Match Me'

Based on a Disqus comment by Asdf (?)
Adding a missing &sect; to an SLS reference in 'Stringy Conversions'

See 09a10e
'Tested with' -> 'First tested with' in puzzler intros

Based on a suggestion by @xhudik
Adding a 'Made obsolete by' item to the puzzler intro for archived puzzlers

Based on a discussion with @xhudik