This is a semi-automated conversion. The first conversion is done using
"pandoc -f html -t rst". The result is then editted manually to apply
the desired heading markup, and fix a few things that pandoc gets wrong.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>