[docs] HowToSubmitABug update?

Hi all,

I was reading through the docs as I wanted to give advice on submitting bug report to clang user asking for help with clang crash at cfe-users mailing list.


I am not really familiar with most of that stuff but the page still mentioned GCC and seems like most of it is 3-5 years old.

It might be worthwhile if someone more knowledgeable could take a look at it.