Enable Renovate unstable and partner GHA runners

- @actions/runner-images
  - macos-26
- @actions/partner-runner-images
  - ubuntu-24.04-arm
  - ubuntu-22.04-arm
- add json5 documentation

Resolve: #1810

Author: leotm

renovate.json5

@@ -40,6 +40,13 @@
       ],
       "addLabels": ["dependencies", "lavamoat"]
     },
+    {
+      // https://github.com/actions/runner-images
+      // https://github.com/actions/partner-runner-images
+      "matchManagers": ["github-actions"],
+      // https://github.com/renovatebot/renovate/tree/main/lib/modules/datasource/github-runners#unstable-runners
+      "ignoreUnstable": false
+    },
     {
       "groupName": "swc monorepo",
       "addLabels": ["devDeps", "swc", "transpiling"],