rustdoc: nodemap doc refreshing
Not pretending to be comprehensive.
- correcting some inconsistencies
- adding a few missing doc-comments
- adding more cross references (in some cases it's right beside
the current documentation item, but it will nevertheless also
be useful, because `rustdoc` will warn us if inconsistencies
arise).
#require docutils gettext
$ $TESTDIR/check-gendoc zh_TW
checking for parse errors