Update non standard validation docs.

doc.go

@@ -993,6 +993,11 @@ that should not make it to production.
 
 Non standard validators
 
+A collection of validation rules that are frequently needed but are more
+complex than the ones found in the baked in validators.
+A non standard validator must be registered manually using any tag you like.
+See below examples of registration and use.
+
 	type Test struct {
 		TestField string `validate:"yourtag"`
 	}

non-standard/validators/notblank.go

@@ -7,7 +7,8 @@ import (
 	"github.com/andreiavrammsd/validator"
 )
 
-// NotBlank is the validation function for validating if the current field has a value or length greater than zero.
+// NotBlank is the validation function for validating if the current field
+// has a value or length greater than zero, or is not a space only string.
 func NotBlank(fl validator.FieldLevel) bool {
 	field := fl.Field()