doc: correct example concerning "hg purge" alias in man page "hgrc.5"
The "hg purge" alias as currently described in "hgrc.5" issues a possibly
confusing error message like
rm: missing operand
Try 'rm --help' for more information.
if no files are to be purged at all.
This patch slightly modifies the example by adding a "-f" option to the
"rm" command.
Test issue2761
$ hg init
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1