doc: soften the NetBSD warning now that a unverified fix is being released

To-be-released NetBSD 7.1.1 reportedly fixes the kernel panic that was
affecting our builders and is being released because of Go's warning.

So, soften our warning.

7.1.1 might work, but I can't get a builder up and running to verify
yet as it appears that Anita either doesn't support it yet, or the
NetBSD CDN doesn't have the files yet.

Change-Id: Ifaafc566879a6afdf1174e545ad10e240da427e8
Reviewed-on: https://go-review.googlesource.com/47970Reviewed-by: Ian Lance Taylor <iant@golang.org>

doc/go1.9.html

@@ -127,14 +127,14 @@ type T1 = T2
 
 <p>
   Go stopped running NetBSD builders during the Go 1.9 development
-  cycle due to persistent hangs and kernel crashes, up to and
-  including NetBSD 7.1. Any help investigating or solving the
-  <a href="https://github.com/golang/go/labels/OS-NetBSD">various
-  NetBSD bugs</a> would be appreciated. In the meantime, we can't
-  recommend running Go on NetBSD.
+  cycle due to NetBSD kernel crashes, up to and including NetBSD 7.1.
+  As Go 1.9 is being released, NetBSD 7.1.1 is being released with a fix.
+  However, at this time we have no NetBSD builders passing our test suite.
+  Any help investigating the
+  <a href="https://github.com/golang/go/labels/OS-NetBSD">various NetBSD issues</a>
+  would be appreciated.
 </p>
 
-
 <h2 id="tools">Tools</h2>
 
 <h3 id="parallel-compile">Parallel Compilation</h3>