It isn’t possible at present to create an account on the LibreOffice help wiki. The regex help is out of date.
The specific change is that this syntax:
should now be:
Apparently trivial … unless you’re actually relying on that page for help!! So, how does one get this corrected? Thanks!
The LibreOffice online help (wikihelp) is generated from the same source that is used to build the help you can install on your computer. So when you want to improve / fix the wikihelp, you actually have to improve / fix the application help itself.
It is in this repository: http://cgit.freedesktop.org/libreoffice/help/
You can contribute the same way as you’d do with code contributions - please see how to setup the access for you here: https://wiki.documentfoundation.org/Development/gerrit
Unfortunately the above is not as straight-forward as editing the help in a real ‘wiki’ way would be; we haven’t yet managed to switch the source the other way around - that the wiki would be the source, and the offline help would be generated from that.
If you get stuck, please go to the IRC (irc.freenode.net), channel #libreoffice-dev, and the people there will help you for sure. Thank you for your interest in helping! - hope the above will work for you 
Many thanks - I’ll see about “tackling” this little tweak to start with; if further help is needed, at least we know where to go. I wonder if it’s worth including something like these instructions on the “How to Participate” section on the main page of the wiki?