[chore] address codeowners to reflect current status (#996)

Co-authored-by: Saad Najmi <saadnajmi2@gmail.com>

.github/CODEOWNERS

@@ -1,3 +1,9 @@
-** @acoates-ms
-** @tom-un
-** @alloy
+# These owners will be the default owners for everything in
+# the repo. Unless a later match takes precedence,
+# the global will be requested for
+# review when someone opens a pull request.
+* @microsoft/apple-rn-team
+
+# React Android specific ones
+/ReactAndroid/ @mganandraj
+/android-patches/ @mganandraj