cppgc: Fix stale comment in build file for example program

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1056170
Change-Id: I0f8d0a4e79fa3a526151efe3317546862aff70bb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2228333
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68144}

BUILD.gn

@@ -4703,7 +4703,7 @@ v8_executable("cppgc_for_v8_embedders") {
 
   configs = [
     # Note: don't use :internal_config here because this target will get
-    # the :external_config applied to it by virtue of depending on :v8, and
+    # the :external_config applied to it by virtue of depending on :cppgc, and
     # you can't have both applied to the same target.
     ":internal_config_base",
   ]