doc: make links for hg role
The system has a bit of smartness:
:hg:`update` -> links to hg.1.html#update
:hg:`help diffs` -> links to hg.1.html#diffs
#!/bin/sh
echo % setting up repo
hg init test
cd test
echo a > a
hg ci -Ama
hg rm a
hg ci -mdel
echo % set up hgweb
hg serve -n test -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
cat hg.pid >> $DAEMON_PIDS
echo % revision
"$TESTDIR/get-with-headers.py" localhost:$HGPORT '/rev/tip'
echo % diff removed file
"$TESTDIR/get-with-headers.py" localhost:$HGPORT '/diff/tip/a'