godoc/dl: remove the tiny, unselectable SHA sums from Featured Downloads
godoc/dl: remove the tiny, unselectable SHA sums from Featured Downloads

The SHA sums are clearly visible (and copy-pastable) in the expanded section
immediately below it.

Fixes golang/go#16900.

Change-Id: If1805534b3893f6c38f4170c4b457ff0e935ce28
Reviewed-on: https://go-review.googlesource.com/33290
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/tools,golang/tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,golang/tools,golang/tools,golang/tools