Updates the tutorial for writing help center articles to encourage
contributors to add to or enhance the existing help center docs
before writing a new articles for new features.
Also, generally updates references to 'user documentation' to be
'help center documentation'.
Additionally, updates some headers within the tutorials for clarity
and consistency, and adds some linkifying throughout the section on
writing documentation.
We recently changed /developer-community to /development-community.
Now that this change is in production, we can also migrate the
external links in our ReadTheDocs documentation.
Lauryn Menard
Eeshan Garg
Anders Kaseorg