gitolite's default "config" option filter is overly conservative, precluding usage of refFilter*Regex options (docs issue)

[pfalcon]

See #118 for background. We tried to use multimailhook.refFilterInclusionRegex option, and had gitolite barf about suspicious chars in option value (a regex). So, we had to adjust UNSAFE_PATT setting in gitolite.rc (see patch below). Again, maybe worth mentioned that in gitolite.rc (just mention that UNSAFE_PATT may need to be adjusted in that file to give user a direction, and let them research and decide what would be "safe" setting for them).

    gitolite.rc: Override and make more liberal UNSAFE_PATT.

    UNSAFE_PATT appears to be used to validate "config" directives in
    gitolite.conf file (i.e. entries to be added to .git/config of
    gitolite-managed repos). This changes is similar REMOTE_COMMAND_PATT
    override applied previously. Specific cause is the need to specify a
    regex for git-multimail hook.

diff --git a/per-service/git-servers/roles/gitolite/templates/gitolite.rc b/per-service/git-servers/roles/gitolite/templates/gitolite.rc
index 1e74588..d7406e1 100644
--- a/per-service/git-servers/roles/gitolite/templates/gitolite.rc
+++ b/per-service/git-servers/roles/gitolite/templates/gitolite.rc
@@ -190,6 +190,7 @@
 # Allow single quote appear in gitolite commands, useful e.g. with "desc"
 # command.
 $REMOTE_COMMAND_PATT = qr(^[-0-9a-zA-Z._\@/+ :,\%=']*$);
+$UNSAFE_PATT         = qr([`~#\&;<>]);

 # ------------------------------------------------------------------------------
 # per perl rules, this should be the last line in such a file:

[moy]

I'm not a gitolite user (I've installed to test git-multimail, but that's all), so I may not be the best person to write the doc. I'll try a patch, but feel free to submit a PR to improve it.