Highlight some basic markdown elements in js/ts fenced code blocks

Fixes #63942

extensions/typescript-basics/package.json

@@ -77,6 +77,16 @@
           "meta.import string.quoted": "other",
           "variable.other.jsdoc": "other"
         }
+      },
+      {
+        "scopeName": "documentation.markdown.injection",
+        "path": "./syntaxes/MarkdownDocumentationInjection.tmLanguage.json",
+        "injectTo": [
+          "source.ts",
+          "source.tsx",
+          "source.js",
+          "source.js.jsx"
+        ]
       }
     ],
     "snippets": [

extensions/typescript-basics/syntaxes/MarkdownDocumentationInjection.tmLanguage.json

@@ -0,0 +1,29 @@
+{
+	"injectionSelector": "L:comment.block.documentation",
+	"patterns": [
+		{
+			"include": "#markdown-comment"
+		}
+	],
+	"repository": {
+		"markdown-comment": {
+			"begin": "^\\s*\\*(?!/)",
+			"while": "(^|\\G)\\s*\\*(?!/)",
+			"patterns": [
+				{
+					"include": "text.html.markdown#fenced_code_block"
+				},
+				{
+					"include": "text.html.markdown#lists"
+				},
+				{
+					"include": "source.ts#docblock"
+				},
+				{
+					"include": "text.html.markdown#inline"
+				}
+			]
+		}
+	},
+	"scopeName": "documentation.markdown.injection"
+}