File::Find: update POD/comments

File::Find: update POD/comments

- change double spaces to single spaces
- remove comment that got lost during the POD reshuffling in f4eedc6b8c8
  (and probably should have been a commit message in the first place)
- remove use of "EG:" that makes no sense to me
- remove reference to hints/machten.sh (removed in e94c1c0554 6 years
  ago)
- change L<The wanted function> to L</The wanted function> because
  that's what internal links should look like according to perlpod
- change S<_> to C<_> (it was S< _> originally but the space got lost
  during a revert, making S<> into a no-op (but why would you write
  S< _> in the first place?))
- link "taint-mode" to perlsec (probably only makes a difference in
  HTML, not man)
- various typo/grammar fixes
- teach podcheck.t about find(1)
- bump version