feat: add input to set version of markdownlint-cli

fix #4

README.md

@@ -12,12 +12,14 @@ files with the `md` or `markdown` extension.
 - uses: articulate/actions-markdownlint@v1
 ```
 
-You can set the config file, the files it scans, or files/directories to ignore.
+You can set the config file, the files it scans, files/directories to ignore, or
+the version of markdownlint-cli to install.
 
 ```yaml
 - uses: articulate/actions-markdownlint@v1
   with:
     config: markdownlint-config.json
     files: 'docs/**/*.md'
     ignore: node_modules
+    version: 0.28.1
 ```

action.yml

@@ -2,6 +2,9 @@ name: markdown-lint
 author: Articulate Global Inc.
 description: Lint your markdown
 inputs:
+  version:
+    description: Version of markdownlint-cli to use
+    required: false
   config:
     description: markdownlint config file
     required: false

entrypoint.sh

@@ -1,5 +1,10 @@
 #!/bin/sh
 
+if [ -n "$INPUT_VERSION" ]; then
+    echo "::debug::installing markdownlint-cli ${INPUT_VERSION}"
+    npm install --global --production "markdownlint-cli@${INPUT_VERSION}"
+fi
+
 # Copy the matcher to a shared volume with the host; otherwise "add-matcher"
 # can't find it.
 if [ "$INPUT_ANNOTATIONS" != "false" ]; then