Add Function to check if string is valid JSON

[naveenraw25]

The isValidJSON function checks if a given string is a valid JSON format. It tries to parse the string and returns true if the parsing is successful and false if an error occurs during the parsing process.

• Added comments to the isValidJSON function to enhance readability and understanding.
• Included examples to demonstrate usage and verify if the string is valid JSON.
• Created README file with a title, description, usage, and examples.