doc/help.html: fix typo in word order

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/87460043

doc/help.html

@@ -39,7 +39,7 @@ Go IRC channel.</p>
 
 <h3 id="twitter"><a href="http://twitter.com/golang">@golang at Twitter</a></h3>
 <p>The Go project's official Twitter account.</p>
-<p>Tweeting your about problem with the <code>#golang</code> hashtag usually
+<p>Tweeting about your problem with the <code>#golang</code> hashtag usually
 generates some helpful responses.</p>
 
 <h3 id="go_user_groups"><a href="/wiki/GoUserGroups">Go User Groups</a></h3>