Flatten codeowners (#1962)

* Flatten codeowners

* Update CODEOWNERS with feedback from the team

.github/CODEOWNERS

@@ -1,12 +1,8 @@
-# directory specific owners
-/.github/               @usnistgov/itl-oscal-maintainers
-/build/                 @usnistgov/itl-oscal-maintainers
-/content/               @aj-stein-nist
-/docs/                  @aj-stein-nist
-/docs/content           @aj-stein-nist @iMichaela
-/json/                  
-/xml/                   
-/src/                   @usnistgov/itl-oscal-maintainers
-/src/metaschema         @aj-stein-nist
-/src/specifications/profile-resolution  @david-waltermire-nist @wendellpiez
-/src/utils              @wendellpiez
+# The OSCAL Admins team governs critical directories
+.github/workflows/      @usnistgov/itl-oscal-admins
+build/Makefile          @usnistgov/itl-oscal-admins
+# The OSCAL Maintainers team governs source and build directories
+src/                    @usnistgov/itl-oscal-maintainers
+build/                  @usnistgov/itl-oscal-maintainers
+# Otherwise governed by the OSCAL Team
+*                       @usnistgov/itl-oscal