fix(markdown): Fix handling of references in Markdown validation

Adds the neccessary schema for referenceType and a corresponding integration test

fixes #159

Author: trieloff

docs/mdast.schema.json

@@ -152,6 +152,15 @@
       "type": ["string", "null"],
       "description": "An alt field should be present. It represents equivalent content for environments that cannot represent the node as intended."
     },
+    "referenceType": {
+      "enum": ["shortcut", "collapsed", "full"],
+      "description": "Represents the explicitness of a reference.",
+      "meta:enum": {
+        "shortcut": "the reference is implicit, its identifier inferred from its content",
+        "collapsed": "the reference is explicit, its identifier inferred from its content",
+        "full": "the reference is explicit, its identifier explicitly set"
+      }
+    },
     "data": {
       "type": "object",
       "description": "data is guaranteed to never be specified by unist or specifications implementing unist. Free data space.",

docs/mdast.schema.md

@@ -30,4 +30,7 @@ It works! {{project.name}} is up and running.
 4. Commit your changes: `git commit -a`
 5. Publish your project to GitHub: `git add git remote add origin https://github.com/user/repo.git && git push`
 6. Deploy the project: `hlx deploy`
-7. Make it visible to the world: `hlx publish`
+7. Make it visible to the world: `hlx publish`
+
+> [!NOTE]
+> This is intended to break.