Merge pull request #46053 from Okabe-Junya/update-ja-reviewer

Add Okabe-Junya to `sig-docs-ja-reviewer`

Author: k8s-ci-robot

OWNERS_ALIASES

@@ -119,6 +119,7 @@ aliases:
     - atoato88
     - bells17
     - kakts
+    - Okabe-Junya
     - t-inu
   sig-docs-ko-owners: # Admins for Korean content
     - gochist