Update documentation of what a "section" is
There are so many slightly different understandings of what a
"section" is or can be. I'm aware the documentation was improved
just a few weeks ago. I still find it incomplete and confusing.
- I renamed it to $sectionId to make it more clear what it
- Sections are usually numbers. 0, 1 and so on. There is no
reason to disallow the use of ints or even floats (this works
because the string representation of 0.0 is "0"). The code never
- 'T1' never was supported, as far as I can tell. 'T-1' is
supported. See Parser::extractSections().
- null and false and '' all mean "the whole page" in
WikiPage::replaceSectionAtRev() but for some reason this meaning got
lost in WikitextContent::replaceSection(). I made it the same again.