feh.1: Silence mandoc warnings

  man -Tlint feh

  STYLE: no blank before trailing delimiter: Em Note:
  WARNING: skipping paragraph macro: Pp after Sh

  no blank before trailing delimiter
    (mdoc) The last argument of a macro that supports trailing
    delimiter arguments is longer than one byte and ends with a
    trailing delimiter. Consider inserting a blank such that the
    delimiter becomes a separate argument, thus moving it out of
    the scope of the macro.

  skipping paragraph macro
    In mdoc(7) documents, this happens

      - at the beginning and end of sections and subsections
      - right before non-compact lists and displays
      - at the end of items in non-column, non-compact lists
      - and for multiple consecutive paragraph macros.

    In man(7) documents, it happens

      - for empty P, PP, and LP macros
      - for IP macros having neither head nor body arguments
      - for br or sp right after SH or SS

  https://man.openbsd.org/mandoc.1

  man: feh.1:1483:9: STYLE: no blank before trailing delimiter: Em Note:
  man: feh.1:1897:2: WARNING: skipping paragraph macro: Pp after Sh

There are two warnings here.

  1. This is fixed by adding a zero-width space (\&) so that the
     trailing delimiter character (:) is no longer at the end.
     This also adds this to a few other similar examples. The man page
     should render the same after this change.

  2. Removed an extra .Pp macro as suggested by the warning, this does
     not change how the man page renders.