provider/aws: add value into ELB name validation message

makes debugging these validation errors much more straightforward

builtin/providers/aws/resource_aws_elb.go

@@ -32,19 +32,20 @@ func resourceAwsElb() *schema.Resource {
 					value := v.(string)
 					if !regexp.MustCompile(`^[0-9A-Za-z-]+$`).MatchString(value) {
 						errors = append(errors, fmt.Errorf(
-							"only alphanumeric characters and hyphens allowed in %q", k))
+							"only alphanumeric characters and hyphens allowed in %q: %q",
+							k, value))
 					}
 					if len(value) > 32 {
 						errors = append(errors, fmt.Errorf(
-							"%q cannot be longer than 32 characters", k))
+							"%q cannot be longer than 32 characters: %q", k, value))
 					}
 					if regexp.MustCompile(`^-`).MatchString(value) {
 						errors = append(errors, fmt.Errorf(
-							"%q cannot begin with a hyphen", k))
+							"%q cannot begin with a hyphen: %q", k, value))
 					}
 					if regexp.MustCompile(`-$`).MatchString(value) {
 						errors = append(errors, fmt.Errorf(
-							"%q cannot end with a hyphen", k))
+							"%q cannot end with a hyphen: %q", k, value))
 					}
 					return
 				},