Support copying workflow as-is to other Prometheus repositories.

Signed-off-by: Charles Korn <charles.korn@grafana.com>

.github/workflows/container_description.yml

@@ -14,7 +14,7 @@ jobs:
   PushDockerHubReadme:
     runs-on: ubuntu-latest
     name: Push README to Docker Hub
-    if: github.repository == 'prometheus/prometheus'
+    if: github.repository_owner == 'prometheus' || github.repository_owner == 'prometheus-community' # Don't run this workflow on forks.
     steps:
       - name: git checkout
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
@@ -34,7 +34,7 @@ jobs:
   PushQuayIoReadme:
     runs-on: ubuntu-latest
     name: Push README to quay.io
-    if: github.repository == 'prometheus/prometheus'
+    if: github.repository_owner == 'prometheus' || github.repository_owner == 'prometheus-community' # Don't run this workflow on forks.
     steps:
       - name: git checkout
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1