tools: consolidate 'introduced_in' check for docs

Author: 1ilsang

doc/api/typescript.md

@@ -10,6 +10,8 @@ changes:
     description: Added `--experimental-transform-types` flag.
 -->
 
+<!--introduced_in=v23.6.0-->
+
 > Stability: 1.1 - Active development
 
 ## Enabling

tools/lint-md/lint-md.mjs

@@ -34,6 +34,14 @@ paths.forEach(async (path) => {
   const fileContents = file.toString();
   const result = await linter.process(file);
   const isDifferent = fileContents !== result.toString();
+
+  if (path.startsWith('doc/api/')) {
+    if (!fileContents.includes('introduced_in')) {
+      console.error(`${path} is missing an 'introduced_in' version. Please add one.`);
+      process.exitCode = 1;
+    }
+  }
+
   if (format) {
     if (isDifferent) {
       fs.writeFileSync(path, result.toString());