Merge topic 'help-formatting'

d1d134534d Help: Add formatting to FindGettext and FindGnuplot
d138555959 Help: Use Title Case for all "Imported Targets" sections
bbbf3536c9 Help: Make sure all deprecated utility modules have a notice
969b039f40 Help: Reference correct variables in 3.6 release notes
9c963de998 Help: Remove stray spaces and one colon
51e4d81f16 Help: Remove accidental blockquotes around lists
718043b540 Help: Convert some literal blocks into tables and lists
914d580a4f Utilities/Sphinx: Ignore warning in generated texinfo documentation

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !10269