Use Github Action to check Markdown links in /docs & /regtests/client…

…/python/docs (apache#141)

.github/workflows/check-md-link-config.json

@@ -0,0 +1,11 @@
+{
+  "ignorePatterns": [
+    {
+      "pattern": "^https?://localhost.*"
+    },
+    {
+      "_comment": "mvnrepository blocks requests originating from GitHub Actions",
+      "pattern": "https://mvnrepository.com/artifact/org.apache.iceberg/iceberg-spark"
+    }
+  ]
+}

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

@@ -0,0 +1,46 @@
+#
+# Copyright (c) 2024 Snowflake Computing Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# This workflow uses actions that are not certified by GitHub.
+# They are provided by a third-party and are governed by
+# separate terms of service, privacy policy, and support
+# documentation.
+# This workflow will find markdown links in the folder paths
+# specified, and confirm the links are valid
+
+name: Check Markdown links
+
+on:
+  push:
+    paths:
+      - '*.md'  # Top-level .md files
+      - docs/**
+      - regtests/README.md
+      - regtests/client/python/docs/**
+      - regtests/client/python/README.md
+    branches:
+      - 'main'
+  pull_request:
+
+jobs:
+  markdown-link-check:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - uses: gaurav-nelson/github-action-markdown-link-check@v1
+      with:
+        config-file: '.github/workflows/check-md-link-config.json'
+        folder-path: '., docs, regtests, regtests/client/python/docs, regtests/client/python'