Before this patch, ":hg:`help config.SECTION`" in online help text is
translated to a link to "hg.1.html#config.SECTION" in HTML
unintentionally.
This patch translates from :hg:`help config.SECTION` in online help
text to a valid link to "hgrc.5.html#SECTION" in HTML.
This patch ignores element(s) under "SECTION" (e.g. "ITEM" of
":hg:`help config.SECTION.ITEM`"), because there is no way to refer
directly to it in HTML, yet.
Before this patch, ":hg:`help config`" in online help text is
translated to a link to "hg.1.html#config" in HTML, even though actual
"hg help config" shows not help for "hg config" command but "config"
help topic, and all of current ":hg:`help config`" expects the latter.
This patch translates from ":hg:`help config`" in online help text to
a link to "hgrc.5.html" in HTML as expected.
This patch also allows ":hg:`help -c COMMAND`" style to link
"hg.1.html#COMMAND" for readability.
Peter Toft told me he had installed a 'python-doc' package instead of
the correct 'python-docutils' and he suggested that we add the URL to
Docutils in our error message.