cmd: improve package docs

Author: dominikh

cmd/gosimple/gosimple.go

@@ -1,4 +1,4 @@
-// gosimple lints the Go source files named on its command line.
+// gosimple detects code that could be rewritten in a simpler way.
 package main // import "honnef.co/go/tools/cmd/gosimple"
 import (
 	"os"

cmd/keyify/keyify.go

@@ -1,3 +1,4 @@
+// keyify transforms unkeyed struct literals into a keyed ones.
 package main
 
 import (

cmd/staticcheck/staticcheck.go

@@ -1,4 +1,5 @@
-// staticcheck statically checks your code for bugs.
+// staticcheck detects a myriad of bugs and inefficiencies in your
+// code.
 package main // import "honnef.co/go/tools/cmd/staticcheck"
 
 import (

cmd/structlayout-optimize/main.go

@@ -1,3 +1,5 @@
+// structlayout-optimize reorders struct fields to minimize the amount
+// of padding.
 package main
 
 import (

cmd/structlayout-pretty/main.go

@@ -1,3 +1,5 @@
+// structlayout-pretty formats the output of structlayout with ASCII
+// art.
 package main
 
 import (

cmd/structlayout/main.go

@@ -1,3 +1,4 @@
+// structlayout displays the layout (field sizes and padding) of structs.
 package main
 
 import (

cmd/unused/main.go

@@ -1,3 +1,5 @@
+// unused reports unused identifiers (types, functions, ...) in your
+// code.
 package main // import "honnef.co/go/tools/cmd/unused"
 
 import (