[docs] Improve docstrings for middleware, skipclean (#375)

middleware.go

@@ -15,7 +15,7 @@ type middleware interface {
 	Middleware(handler http.Handler) http.Handler
 }
 
-// Middleware also implements the middleware interface.
+// Middleware allows MiddlewareFunc to implement the middleware interface.
 func (mw MiddlewareFunc) Middleware(handler http.Handler) http.Handler {
 	return mw(handler)
 }

mux.go

@@ -13,7 +13,7 @@ import (
 )
 
 var (
-	// ErrMethodMismatch is returned when the error in the request does not match
+	// ErrMethodMismatch is returned when the method in the request does not match
 	// the method defined against the route.
 	ErrMethodMismatch = errors.New("method is not allowed")
 	// ErrNotFound is returned when no route match is found.

route.go

@@ -43,8 +43,8 @@ type Route struct {
 	buildVarsFunc BuildVarsFunc
 }
 
-// SkipClean bypasses cleaning the path, which includes removing duplicate
+// SkipClean reports whether path cleaning is enabled for this route via
-// slashes and URL encoding.
+// Router.SkipClean.
 func (r *Route) SkipClean() bool {
 	return r.skipClean
 }