Updated project README to include references to the new security policy.

Moved the project's code of conduct out of the contributions guide and into the appropriate policy file.

Updated the contribution guide to follow the NetBox project format.

Added various issue templates based on the NetBox project formats but updated for PDA.

Added additional GitHub workflows to handle stale and closed issue and PR management.

Removed legacy stale issue workflow that was not in use.

.github/workflows/lock.yml

@@ -0,0 +1,21 @@
+# lock-threads (https://github.com/marketplace/actions/lock-threads)
+name: 'Lock threads'
+
+on:
+  schedule:
+    - cron: '0 3 * * *'
+  workflow_dispatch:
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  lock:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: dessant/lock-threads@v3
+        with:
+          issue-inactive-days: 90
+          pr-inactive-days: 30
+          issue-lock-reason: 'resolved'

.github/workflows/stale.yml

@@ -0,0 +1,45 @@
+# close-stale-issues (https://github.com/marketplace/actions/close-stale-issues)
+name: 'Close stale issues/PRs'
+
+on:
+  schedule:
+    - cron: '0 4 * * *'
+  workflow_dispatch:
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  stale:
+
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v6
+        with:
+          close-issue-message: >
+            This issue has been automatically closed due to lack of activity. In an
+            effort to reduce noise, please do not comment any further. Note that the
+            core maintainers may elect to reopen this issue at a later date if deemed
+            necessary.
+          close-pr-message: >
+            This PR has been automatically closed due to lack of activity.
+          days-before-stale: 90
+          days-before-close: 30
+          exempt-issue-labels: 'status: accepted,status: blocked,status: needs milestone'
+          operations-per-run: 100
+          remove-stale-when-updated: false
+          stale-issue-label: 'mod / stale'
+          stale-issue-message: >
+            This issue has been automatically marked as stale because it has not had
+            recent activity. It will be closed if no further activity occurs. PDA
+            is governed by a small group of core maintainers which means not all opened
+            issues may receive direct feedback. **Do not** attempt to circumvent this
+            process by "bumping" the issue; doing so will result in its immediate closure
+            and you may be barred from participating in any future discussions. Please see
+            our [contributing guide](https://github.com/PowerDNS-Admin/PowerDNS-Admin/blob/docs/CONTRIBUTING.md).
+          stale-pr-label: 'mod / stale'
+          stale-pr-message: >
+            This PR has been automatically marked as stale because it has not had
+            recent activity. It will be closed automatically if no further action is
+            taken.