Add Solution of "minimum-add-to-make-parentheses-valid" & Update README.md

[yarncha]

Pull Request Template

Description

Like many other parentheses questions, this question is a stack problem. To solve it, I should calculate how many parentheses are needed. The input value of this question is a parentheses string, so I checked it's characters one by one and push&pop parentheses to stack.

Put check marks:

Have you made changes in README file ?

• Added problem & solution under correct topic.
• Specified Space & Time complexity.
• Specified difficulty level, tag & Note(if any).

How Has This Been Tested?

Used these inputs to test code.

• S = "(()))(("
• S = "))(("

Make sure all below guidelines are followed else PR will get Reject:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code so that it is easy to understand
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[welcome]

I can tell this is your first pull request! Thank you I'm so honored. 🎉🎉🎉 I'll take a look at it ASAP!

[welcome]

Your code looks great! Congrats, I've gone ahead and merged your first pull request! Keep it up!