[PATCH] Add a stub CONTRIBUTING.md pointing to the wiki


Googling for 'edk2 pull request' did not find this wiki page:


Add it to CONTRIBUTING.md for more discoverability

Signed-off-by: Cole Robinson <crobinso@...>
I tried submitting a PR to edk2: https://github.com/tianocore/edk2/pull/854

It was auto closed with: `All checks passed. Auto close personal build.`

That confused me quite a bit. I could not understand what it was trying
to say. I looked at other successfully merged PRs, noticed some hits
about a 'push' label, but on looking to resubmit the PR it didn't seem
like I had permission to set labels. Googling did not turn up any explanatory
hits in the first two pages either. Eventually Laszlo pointed me in the
right direction though

A couple other suggestions to avoid that confusion

* Extend the mergify message to clarify PRs are largely only meant for
maintainers to use. Maybe point at the wiki page or CONTRIBUTING.md

* Add a github new PR template with a comment giving more explanation:

1 file changed, 3 insertions(+)
create mode 100644 CONTRIBUTING.md

new file mode 100644
index 0000000000..212c69ce8b
--- /dev/null
@@ -0,0 +1,3 @@
+# Contributing to EDK2
+Contributor documentation is maintained on the wiki: https://github.com/tianocore/tianocore.github.io/wiki/EDK-II-Development-Process

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