New stories button alignment

[PriyanshuGarg26]

Issue Number

fixes #157

Describe the changes you've made Added a btn-text-center class name in New story button in Navigation.js and add the required styles in navigation.scss file.

Describe if there is any unusual behavior (Any Warning) of your code(Write NA if there isn't) NA

Checklist

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] All new and existing tests passed.
• [x] The title of my pull request is a short description of the requested changes.