Improve Renovate behavior (#689)

- Add Gitea releases for `appVersion`
- Rewrite Helm changelog url to retrieve release notes

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/689
Reviewed-by: pat-s <pat-s@noreply.gitea.com>
Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Co-committed-by: justusbunsi <sk.bunsenbrenner@gmail.com>

renovate.json5

@@ -30,6 +30,14 @@
       ],
       datasourceTemplate: 'github-releases',
     },
+    {
+      'description': 'Automatically detect new Gitea releases',
+      'customType': 'regex',
+      'fileMatch': ['(^|/)Chart\\.yaml$'],
+      'matchStrings': [
+        '# renovate datasource=(?<datasource>\\S+) depName=(?<depName>\\S+) extractVersion=(?<extractVersion>\\S+)\\nappVersion:\\s?(?<currentValue>\\S+)\\n',
+      ],
+    },
   ],
   packageRules: [
     {
@@ -56,5 +64,12 @@
         'digest',
       ],
     },
+    {
+      description: 'Override changelog url for Helm image, to have release notes in our PRs',
+      matchDepNames: [
+        'alpine/helm',
+      ],
+      changelogUrl: 'https://github.com/helm/helm',
+    },
   ],
 }