doc/go1.10: note that plugin now works on darwin/amd64

Fixes #23085

Change-Id: I7fef281079e9e08c49ae05371506b0b881a467db
Reviewed-on: https://go-review.googlesource.com/83577
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: bradfitz

doc/go1.10.html

@@ -437,7 +437,7 @@ <h3 id="compiler">Compiler Toolchain</h3>
 has been ported to more systems.
 Specifically, <code>c-shared</code> now works on <code>linux/ppc64le</code>, <code>windows/386</code>, and <code>windows/amd64</code>;
 <code>pie</code> now works on <code>darwin/amd64</code> and also forces the use of external linking on all systems;
-and <code>plugin</code> now works on <code>linux/ppc64le</code>.
+and <code>plugin</code> now works on <code>linux/ppc64le</code> and <code>darwin/amd64</code>.
 </p>
 
 <p>