MAINT: Add CODEOWNERS

CODEOWNERS

@@ -0,0 +1,13 @@
+# This is a comment.
+# Each line is a file pattern followed by one or more owners.
+
+# These owners will be the default owners for everything in
+# the repo. Unless a later match takes precedence,
+# @global-owner1 and @global-owner2 will be requested for
+# review when someone opens a pull request.
+*       @HaoZeke
+
+# Order is important; the last matching pattern takes the most
+# precedence. When someone opens a pull request that only
+# modifies JS files, for example, only @js-owner and not the global
+# owner(s) will be requested for a review.