* fix grad norm formula
* grad-norm tracker test
* fixed seed and explicit rtol in grad norm tracking test
* a docstring for grad-norms and forced cast to float of norm_type
* support for inf-norm
* renamed the grad norm test
* docs
* fixed language in docstring
* Apply suggestions from code review
Co-authored-by: Jirka <jirka@pytorchlightning.ai>
Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Ivan Nazarov