arm port description.

R=r
http://go/go-review/1026010

doc/install.html

@@ -106,9 +106,8 @@ architectures.
 	<code>arm</code> (a.k.a. <code>ARM</code>); <code>5g,5l,5c,5a</code>
 </dt>
 <dd>
-	Developed under the QEMU emulation environment, this is the
-	newest implementation.  It's got a couple of outstanding bugs
-	but is improving.
+	It's got a couple of outstanding bugs but is improving. Tested against QEMU
+	and an android phone.
 </dd>
 </dl>