cmd/go: run mkalldocs.sh after earlier revert

Change-Id: Ie4ed8b3e7d26ae53b2290a7a6e7d9888eb963edc
Reviewed-on: https://go-review.googlesource.com/130318
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/go/alldocs.go

@@ -1005,16 +1005,13 @@
 //
 // Usage:
 //
-// 	go mod graph [-dot]
+// 	go mod graph
 //
 // Graph prints the module requirement graph (with replacements applied)
 // in text form. Each line in the output has two space-separated fields: a module
 // and one of its requirements. Each module is identified as a string of the form
 // path@version, except for the main module, which has no @version suffix.
 //
-// The -dot flag generates the output in graphviz format that can be used
-// with a tool like dot to visually render the dependency graph.
-//
 //
 // Initialize new module in current directory
 //