* Add map object `extToMimes` to map file extensions to MIME types.

src/mimes.ts

@@ -0,0 +1,10 @@
+const extToMimes = new Map(
+  Object.entries({
+    html: "text/html",
+    xhtml: "application/xhtml+xml",
+    xml: "application/xml",
+  })
+);
+Object.freeze(extToMimes);
+
+export default extToMimes;