* I've never heard the term "pFCP" used before, so spell it out as
"proposed final comment period"
* Fix some unclear things (like implying that you need `r+` rights to
start an FCP)
* Improve the chapter's title, and make it consistent with its TOC entry
* Make some other assorted minor cleanups and improvements
* Updated instructions for tracking issue
Removed link to Forge instructions for documentation since they no longer seem to exist.
* Improved links and wording
When I recently searched for infos in this guide on how to create
a warning, I couldn't find any. Later I found it through #14.
The reason was that I didn't know the term 'diagnostics' and that
it is the collective term for errors, warnings and lints.
Renaming the chapter to include the word 'error' should help.
I think also including 'warning' in the title shouldn't be
neccessary, because it's close enought.