It should say "textDocument/foldingRange" even though everyone names
the associated function FoldingRanges.
Change-Id: I79c8449a689dc8c80f745c875d9ec9892d926e9c
Reviewed-on: https://go-review.googlesource.com/c/155578
Reviewed-by: Ian Cottrell <iancottrell@google.com>