OWNERS.md: add microsite to the scope of the documentation area

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.github/CODEOWNERS

@@ -15,6 +15,8 @@ yarn.lock                                         @backstage/maintainers @backst
 /docs/dls                                         @backstage/design-system-maintainers
 /docs/features/techdocs                           @backstage/techdocs-maintainers
 /docs/plugins/integrating-search-into-plugins.md  @backstage/search-maintainers
+/microsite                                        @backstage/documentation-maintainers
+/microsite/data/plugins                           @backstage/maintainers
 /packages/cli/src/commands/onboard                @backstage/sharks
 /packages/backend-openapi-utils                   @backstage/maintainers @backstage/reviewers @backstage/openapi-tooling-maintainers
 /packages/canon                                   @backstage/design-system-maintainers

.github/advanced-issue-labeler.yml

@@ -14,7 +14,7 @@ policy:
           - name: 'area:design-system'
             keys: ['Design System']
           - name: 'area:documentation'
-            keys: ['Documentation']
+            keys: ['Documentation', 'Microsite']
           - name: 'area:events'
             keys: ['Events System']
           - name: 'area:home'