add example for maxLength keyword demonstrating string length validation with unicode characters

Author: AgniveshChaubey

content/2020-12/validation/maxLength.markdown

@@ -61,4 +61,20 @@ The `maxLength` keyword is used to specify the maximum length of a string instan
 
 {{<instance-pass `An instance with a numeric value is valid`>}}
 55
-{{</instance-pass>}}
+{{</instance-pass>}}
+
+{{<schema `Schema for maximum string length validation with unicode characters`>}}
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "string",
+  "maxLength": 3
+}
+{{</schema>}}
+
+{{<instance-pass `An instance with 3 or less characters is valid`>}}
+"\u0066\u006F\u006F" // --> "foo"
+{{</instance-pass>}}
+
+{{<instance-fail `An instance with more than 3 characters is invalid`>}}
+"\u0048\u0065\u006C\u006C\u006F" // --> 'Hello'
+{{</instance-fail>}}