add dependabot for GHA and linkchecker

.github/dependabot.yml

@@ -0,0 +1,11 @@
+# See https://docs.github.com/en/code-security/supply-chain-security/keeping-your-dependencies-updated-automatically/keeping-your-actions-up-to-date-with-dependabot
+
+version: 2
+updates:
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    labels:
+      - "Bot"

.github/workflows/md-link-check.yml

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+name: Check Markdown links
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  markdown-link-check:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: checkout
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Check gh-pages
+      if: github.ref == 'refs/heads/gh-pages'
+      uses: gaurav-nelson/github-action-markdown-link-check@v1
+      with:
+        use-quiet-mode: 'yes'
+        use-verbose-mode: 'yes'
+        config-file: 'mlc_config.json'
+        file-path: './README.md'
+        folder-path: '_docs/'
+
+    - name: Check main
+      uses: gaurav-nelson/github-action-markdown-link-check@v1
+      with:
+        use-quiet-mode: 'yes'
+        use-verbose-mode: 'yes'
+        file-path: './README.md'

.github/workflows/mlc_config.json

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+{
+  "ignorePatterns": [
+    {
+      "pattern": "://localhost"
+    }
+  ],
+  "aliveStatusCodes": [200, 0]
+}