[ci] Add a `.buildkite` entry to `CODEOWNERS`.
While not strictly necessary, I suspect those who are more keen on
our release mechanics might want this called out specifically.
Additionally, I added myself to the `tools/` directory.
* @reset @fnichol @christophermaier
+.buildkite @christophermaier @fnichol
components/backline @fnichol @baumanj
components/builder* @chefsalim @raskchanky
components/butterfly* @christophermaier @reset @baumanj
@@ -11,5 +12,5 @@ components/plan-build @fnichol @christophermaier @elliott-davis
components/studio @fnichol @baumanj @elliott-davis
components/sup @christophermaier @reset @fnichol @baumanj
support @fnichol @baumanj @elliott-davis @raskchanky
-tools @baumanj @chefsalim @christophermaier @eeyun @raskchanky
+tools @baumanj @chefsalim @christophermaier @eeyun @raskchanky @fnichol
www @cnunciato @mgamini @raskchanky
