cmd: update formatting of usage messages
R=golang-dev, r, minux.ma
CC=golang-dev
https://golang.org/cl/5738045
diff --git a/src/cmd/yacc/doc.go b/src/cmd/yacc/doc.go
index 9874a2a..4a2c2a3 100644
--- a/src/cmd/yacc/doc.go
+++ b/src/cmd/yacc/doc.go
@@ -4,10 +4,13 @@
/*
-Yacc is a version of yacc for Go. It is run with the command
- go tool yacc args...
+Yacc is a version of yacc for Go.
It is written in Go and generates parsers written in Go.
+Usage:
+
+ go tool yacc args...
+
It is largely transliterated from the Inferno version written in Limbo
which in turn was largely transliterated from the Plan 9 version
written in C and documented at
