Corrected Mojo typemap code example

Change-Id: I92a979d500490786dc0c33d30bc653fa1cee214b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1825379
Auto-Submit: Matthew Denton <mpdenton@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#700281}

mojo/public/cpp/bindings/README.md

@@ -1383,7 +1383,6 @@ And in `//ui/gfx/geometry/mojo/geometry_mojom_traits.cc`:
 namespace mojo {
 
 // static
-template <>
 bool StructTraits<gfx::mojom::RectDataView, gfx::Rect>::Read(
     gfx::mojom::RectDataView data,
   gfx::Rect* out_rect) {