[clang-tools-extra] added option `google-readability-namespace-comments.AllowNoNamespaceComments` (PR #124265)

[Baranov Victor via cfe-commits]

vbvictor wrote:

 > What do you think about the option's name? Is `AllowNoNamespaceComments` fine for you or shall I rename to `AllowOmittingNamespaceComments` (or any other suggestion)?

As for now I can not think of a better name, maybe others will suggest.

https://github.com/llvm/llvm-project/pull/124265