doc: add missing article

Change-Id: I73fdc793bbc3ffe9ace1bfa78799f84c31630d61
Reviewed-on: https://go-review.googlesource.com/48391Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

doc/go1.9.html

@@ -233,7 +233,7 @@ type T1 = T2
   Profiles produced by the <code>runtime/pprof</code> package now
   include symbol information, so they can be viewed
   in <code>go</code> <code>tool</code> <code>pprof</code>
-  without binary that produced the profile.
+  without the binary that produced the profile.
 </p>
 
 <p> <!-- CL 38343 -->
@@ -520,7 +520,7 @@ version of gccgo.
 
 <dl id="encoding/base32"><dt><a href="/pkg/encoding/base32/">encoding/base32</a></dt>
   <dd>
-    <p><!-- CL 38634 --> 
+    <p><!-- CL 38634 -->
 	  The new <a href="/pkg/encoding/base32/#Encoding.WithPadding">Encoding.WithPadding</a>
 	  method adds support for custom padding characters and disabling padding.
     </p>
@@ -913,7 +913,7 @@ version of gccgo.
       interface describes some types in the
       <a href="/pkg/net/"><code>net</code></a>
       package that can provide access to their underlying file descriptor
-      using the new 
+      using the new
       <a href="/pkg/syscall/#RawConn"><code>RawConn</code></a>
       interface.
     </p>
@@ -955,7 +955,7 @@ version of gccgo.
     <p><!-- CL 36615 -->
       The new methods
       <a href="/pkg/time/#Duration.Round"><code>Duration.Round</code></a>
-      and 
+      and
       <a href="/pkg/time/#Duration.Truncate"><code>Duration.Truncate</code></a>
       handle rounding and truncating durations to multiples of a given duration.
     </p>
@@ -978,4 +978,3 @@ version of gccgo.
     </p>
 
 </dl><!-- time -->
-