Adapted behaviour of ui.username() to documentation and mention it explicitly:
Searched in this order: $HGUSER, [ui] section of hgrcs, $EMAIL
and stop searching if one of these is set.
Abort if found username is an empty string to force specifying
the commit user elsewhere, e.g. with line option or repo hgrc.
If not found, use $LOGNAME or $USERNAME +"@full.hostname".
Mercurial's documentation is currently kept in ASCIIDOC format, which
is a simple plain text format that's easy to read and edit. It's also
convertible to a variety of other formats including standard UNIX man
page format and HTML.
To do this, you'll need to install ASCIIDOC:
http://www.methods.co.nz/asciidoc/
To generate the man page:
asciidoc -d manpage -b docbook hg.1.txt
xmlto man hg.1.xml
To display:
groff -mandoc -Tascii hg.1 | more
To create the html page (without stylesheets):
asciidoc -b html hg.1.txt