doc: fix typo in diagnostic tooling support tiers document

PR-URL: #54058
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: kimtaejin3

doc/contributing/diagnostic-tooling-support-tiers.md

@@ -26,7 +26,7 @@ the following tiers.
     organization or website;
   * The tool must be working on all supported platforms;
   * The tool must only be using APIs exposed by Node.js as opposed to
-    its dependencies; and
+    its dependencies;
   * The tool must be open source.
 
 * Tier 2 - Must be working (CI tests passing) for all