cmd/go: run mkalldocs.sh

This should have happened as part of CL 28485.

Change-Id: I63cd31303e542ceaec3f4002c5573f186a1e9a52
Reviewed-on: https://go-review.googlesource.com/28547
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/alldocs.go

@@ -17,6 +17,7 @@
 // 	clean       remove object files
 // 	doc         show documentation for package or symbol
 // 	env         print Go environment information
+// 	bug         print information for bug reports
 // 	fix         run go tool fix on packages
 // 	fmt         run gofmt on package sources
 // 	generate    generate Go files by processing source
@@ -323,6 +324,17 @@
 // each named variable on its own line.
 //
 //
+// Print information for bug reports
+//
+// Usage:
+//
+// 	go bug
+//
+// Bug prints information that helps file effective bug reports.
+//
+// Bugs may be reported at https://golang.org/issue/new.
+//
+//
 // Run go tool fix on packages
 //
 // Usage: