doc: fix a typo

Change-Id: Ia830f59d6f6ca1bc506ec298ccfc154d9f94f01d
GitHub-Last-Rev: 3ab18d4fd1a8d4295713cbb7ff74f30b3838b6d3
GitHub-Pull-Request: golang/go#30067
Reviewed-on: https://go-review.googlesource.com/c/160829
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

doc/codewalk/codewalk.js

@@ -276,7 +276,7 @@ CodewalkViewer.prototype.changeSelectedComment = function(target) {
   }
 
   // Force original file even if user hasn't changed comments since they may
-  // have nagivated away from it within the iframe without us knowing.
+  // have navigated away from it within the iframe without us knowing.
   this.navigateToCode(currentFile);
 };