Update ParseUnverified godoc (#341)

parser.go

@@ -117,8 +117,8 @@ func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyf
 //
 // WARNING: Don't use this method unless you know what you're doing.
 //
-// It's only ever useful in cases where you know the signature is valid (because it has
-// been checked previously in the stack) and you want to extract values from it.
+// It's only ever useful in cases where you know the signature is valid (since it has already
+// been or will be checked elsewhere in the stack) and you want to extract values from it.
 func (p *Parser) ParseUnverified(tokenString string, claims Claims) (token *Token, parts []string, err error) {
 	parts = strings.Split(tokenString, ".")
 	if len(parts) != 3 {