help: properly document the default pattern
The default isn't to glob. It's relpath, which does no globbing at
all. Thus most commands and options like -X/-I and hg files require
`glob:` in front of them to actually do any globbing.
I think long ago the default was to glob, but that hasn't been true
for a long time.
# Files that just need to be migrated to the formatter.
# Do not add new files here!
mercurial/cext/manifest.c
mercurial/cext/osutil.c
# Vendored code that we should never format:
syntax: glob
contrib/python-zstandard/**.c
contrib/python-zstandard/**.h
hgext/fsmonitor/pywatchman/**.c
mercurial/thirdparty/**.c
mercurial/thirdparty/**.h
mercurial/pythoncapi_compat.h