[Buildroot] [PATCH 0/4] docs: improve submitting patches

[Arnout Vandecappelle (Essensium/Mind)]

I've seen Thomas P. send a few feedback e-mails recently that give basic
explanation to newcomers about how patches should be formatted when
sending them to buildroot. So let's improve the documentation to avoid
this in the future, or to make it easier to just refer to
https://buildroot.org/manual.html#submitting-patches