In https://github.com/angular/angular/pull/33058, we removed support
for the `ngForm` selector in the NgForm directive. We deleted most
of the deprecation notices in that PR, but we missed a paragraph
of documentation in the API docs for NgForm.
This commit removes the outdated paragraph that makes it seem like
the selector is still around and deprecated (as opposed to removed),
as it might confuse users.
PR Close#35435