Add Bazel partners, so that the left sidebar navigation is shown on the page.

PiperOrigin-RevId: 570657155
Change-Id: I1d80c0d42ca22a685839b5d79ccd8be22d016a26

Author: meisterT

site/en/_book.yaml

@@ -361,6 +361,8 @@ upper_tabs:
         path: /community/sig
       - title: Bazel experts
         path: /community/experts/
+      - title: Bazel partners
+        path: /community/partners/
       - title: Bazel users
         path: /community/users
       - title: Nominate a recommended rule