install doc: arm is a little better

R=adg, r, r2
CC=golang-dev
https://golang.org/cl/2749041

doc/install.html

@@ -45,8 +45,11 @@ architectures.
 </dt>
 <dd>
 	Incomplete.
-	It only supports Linux binaries, floating point is weak,
-	it has code generation bugs, and the optimizer is not enabled.
+	It only supports Linux binaries, the optimizer is not enabled,
+	and floating point is performed entirely in software.
+	However, all tests pass.
+	Work on the optimizer and use of the VFP hardware
+	floating point unit is underway.
 	Tested against a Nexus One.
 </dd>
 </dl>