Welcome, David. We're always looking for writers! Whether writing
something new or updating/improving existing material, we have a lot
of things that need to be done.
The first step is to subscribe to this list. To do that, send an email
to documentation+subscribe@global.libreoffice.org
Some general information is on this wiki page:
https://wiki.documentfoundation.org/Documentation/Development
See especially the links in the "First Steps" section of that page.
Do you have a particular interest in some topic, such as spreadsheets,
presentations, databases? How much experience have you had with
LibreOffice itself? No answers to these questions are "wrong" because
we can use people at all levels of experience and knowledge.
--Jean