doc: document default test-reporter change

Document the change made in #54548

PR-URL: #58302
Fixes: #58301
Refs: #54548
Reviewed-By: Tierney Cyren <[email protected]>
Reviewed-By: Jacob Smith <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Pietro Marchini <[email protected]>

Author: nicojs

doc/api/test.md

@@ -1046,6 +1046,10 @@ added:
   - v19.6.0
   - v18.15.0
 changes:
+  - version: v23.0.0
+    pr-url: https://github.com/nodejs/node/pull/54548
+    description: The default reporter on non-TTY stdout is changed from `tap` to
+                 `spec`, aligning with TTY stdout.
   - version:
     - v19.9.0
     - v18.17.0