Update README.md

Author: harmeetsingh11

Diff for: 2618-check-if-object-instance-of-class/README.md

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-<h2><a href="https://leetcode.com/problems/check-if-object-instance-of-class/">2618. Check if Object Instance of Class</a></h2><h3>Medium</h3><hr><div><p>Write a function that checks if a given value&nbsp;is an instance of a given class or superclass. For this problem, an object is considered an instance of a given class if that object has access to that class's methods.</p>
+<h2><a href="https://leetcode.com/problems/check-if-object-instance-of-class/">2618. Check if Object Instance of Class</a></h2><img src="https://img.shields.io/badge/Medium-FECC00" alt="Medium" /><hr><div><p>Write a function that checks if a given value&nbsp;is an instance of a given class or superclass. For this problem, an object is considered an instance of a given class if that object has access to that class's methods.</p>
 
 <p>There are&nbsp;no constraints on the data types that can be passed to the function. For example, the value or the class could be&nbsp;<code>undefined</code>.</p>
 
@@ -34,4 +34,4 @@ Dog is a subclass of Animal. Therefore, a Dog object is an instance of both Dog
 <strong>Output:</strong> true
 <strong>Explanation: </strong>5 is a Number. Note that the "instanceof" keyword would return false. However, it is still considered an instance of Number because it accesses the Number methods. For example "toFixed()".
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