Point the repo at projectcalico/calico for master development

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Report a bug or request a feature
+    url: https://github.com/projectcalico/calico/issues/new/choose
+    about: The operator is developed in the projectcalico/calico repository. Please file here.
+  - name: Ask a question
+    url: https://slack.projectcalico.org
+    about: Questions and discussion with the Calico community on Slack.

.github/workflows/sync-versions.yml

@@ -20,12 +20,12 @@ jobs:
       - name: Discover branches
         id: branches
         run: |
-          # Get master + the two most recent release branches (by semver).
+          # Get the two most recent release branches (by semver). master is not
+          # released from, so it is skipped.
           branches=$(gh api repos/${{ github.repository }}/branches --paginate --jq '
             [.[] | select(.name | test("^release-v[0-9]+\\.[0-9]+$")) | .name]
             | sort_by(ltrimstr("release-v") | split(".") | map(tonumber))
             | .[-2:]
-            | ["master"] + .
           ')
           echo "branches=${branches}" >> "$GITHUB_OUTPUT"
         env:

README.md

@@ -2,6 +2,9 @@
 
 [![Docker image](https://img.shields.io/badge/docker-quay.io%2Ftigera%2Foperator-blue)](https://quay.io/repository/tigera/operator)
 
+> **The operator is developed in [projectcalico/calico](https://github.com/projectcalico/calico/tree/master/operator).**
+> The `master` branch in this repository is no longer maintained. Bugs, feature requests, and pull requests go to projectcalico/calico. This repository still serves the `release-v1.41` through `release-v1.44` branches for the rest of their supported lives.
+
 This repository contains a Kubernetes operator which manages the lifecycle of a Calico or Calico Enterprise installation on Kubernetes or OpenShift. Its goal is
 to make installation, upgrades, and ongoing lifecycle management of Calico and Calico Enterprise as simple and reliable as possible.