<issue_start><issue_comment>Title: Stack implementation #854
username_0: <hr>

## Description 📜

I created a readme file with images ,which describes stack briefly. Along with that I attached code snippets of implementation of stack using arrays as well as using linked list. # <854> 

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## Type of change 📝

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- [x] Documentation (Content Creation in the form of codes or tutorials)

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## Domain of Contribution 📊

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- [x] C/CPP

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## Checklist ✅

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- [x] I follow [Contributing Guidelines](https://github.com/girlscript/winter-of-contributing/blob/main/.github/CONTRIBUTING.md) & [Code of conduct](https://github.com/girlscript/winter-of-contributing/blob/main/.github/CODE_OF_CONDUCT.md) of this project.
- [x] I have performed a self-review of my own code or work.
- [x] I have commented my code, particularly in hard-to-understand areas.
- [x] My changes generates no new warnings.
- [x] I'm GWOC'21 contributor

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## Screenshots / Gif (Optional) 📸

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<issue_comment>username_1: @username_0 Way to go :octocat: