add linter + renovate (#6)

### 📖 Summary

- add renovate json
- add linters:
  - Dockerfile
  - markdown
  - editorconfig

### 📑 Test Plan

✅ CI pipeline tests (Default)

### 💬 Details

_No response_

### 📚 Additional Notes

_No response_

Reviewed-on: #6

.woodpecker/ci.yml

@@ -26,6 +26,28 @@ variables:
         from_secret: gitea_passwd
 
 steps:
+  lint-dockerfile:
+    image: hadolint/hadolint:v2.12.1-beta-alpine
+    commands:
+      #- cat Dockerfile
+      #- hadolint --verbose --ignore DL3003 --ignore DL3018 Dockerfile
+      - hadolint --ignore DL3003 --ignore DL3018 Dockerfile
+    #when:
+    #  path: "Dockerfile"
+
+  lint-markdown:
+    image: davidanson/markdownlint-cli2:v0.13.0
+    commands:
+      - "markdownlint-cli2 *.{md,markdown}"
+    when:
+      path: "*.{md,markdown}"
+
+  lint-editorconfig:
+    depends_on: []
+    image: docker.io/mstruebing/editorconfig-checker:v3.0.1
+    when:
+      event: pull_request
+
   test:
     image: *build_plugin
     settings: