Added remark about stashing untracked files

basic/index.html

@@ -849,6 +849,12 @@ nothing to commit (working directory clean)
     It will then leave you at the state of the last commit.
     </p>
 
+    <p>If you have untracked files, <code>git stash</code> doesn't save it. You
+    can either add stage those files with <code>git add</code> (you don't have
+    to commit) before stashing, or, if you have a recent Git version (1.7.7 or
+    above), you can use <code>git stash -u</code> to stash also unversioned
+    files.</p>
+
 <pre>
 <b>$ git status -s</b>
 <span class="red">M</span> hello.rb