Update docs for \output_changes move

Update docs for \output_changes move

Since \output_changes is written again at the original position, we need to
fix those files that have been updated using the intermediate version.
The update was done by running development/tools/updatedocs.py <lyxexe> where
<lyxexe> was the path to an up to date LyX binary. All files that did contain
additional changes were reverted:

lib/doc/LFUNs.lyx
lib/doc/UserGuide.lyx
lib/doc/Shortcuts.lyx
lib/examples/de/beamer.lyx

The \SpecialChar changes are fine, these files have never been saved by LyX
after the update to 483.