update documentation with usage of gdb

[naseemkullah]

Documentation actually states that gdb is not yet supported.

However this repo says it is, would it be possible to update docs and add instructions on gdb debugging?

Cheers!

[naseemkullah]

I suppose it is in the works as per https://github.com/solo-io/squash/blob/master/next_docs.md ?

[mitchdraft]

thanks for the reminder, I've updated the docs, let me know if you have any questions https://squash.solo.io/debuggers/gdb/