Fix typos and add missing documentation

errors.go

@@ -54,6 +54,7 @@ func (r *ConnectionRejectedError) Error() string {
 	return r.reason
 }
 
+// StatusCode returns the HTTP status code for the connection rejection.
 func (r *ConnectionRejectedError) StatusCode() int {
 	return r.code
 }

server.go

@@ -281,9 +281,9 @@ type Upgrader struct {
 	// The argument is only valid until the callback returns.
 	Protocol func([]byte) bool
 
-	// ProtocolCustrom allow user to parse Sec-WebSocket-Protocol header manually.
+	// ProtocolCustom allows users to parse Sec-WebSocket-Protocol header manually.
 	// Note that returned bytes must be valid until Upgrade returns.
-	// If ProtocolCustom is set, it used instead of Protocol function.
+	// If ProtocolCustom is set, it is used instead of Protocol function.
 	ProtocolCustom func([]byte) (string, bool)
 
 	// Extension is a select function that is used to select extensions

wsutil/utf8.go

@@ -22,7 +22,7 @@ var ErrInvalidUTF8 = fmt.Errorf("invalid utf8")
 // Another possible case is when some valid sequence become split by the read
 // bound. Then UTF8Reader can not make decision about validity of the last
 // sequence cause it is not fully read yet. And if the read stops, Valid() will
-// return false, even if Read() by itself dit not.
+// return false, even if Read() by itself did not.
 type UTF8Reader struct {
 	Source io.Reader