update README.md

[annabelaruiz111]

Description

Created introduction, features, and requirements sections to README.md, and added clarifications and elaborations to existing sections.

Motivation and Context

This change makes using Vue-Carousel more accessible by providing a more detailed explanation of the features it provides and how to use them.

How Has This Been Tested?

This commit was not tested since it was a documentation only change.

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Documentation change

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [ ] I have included a vue-play example (if this is a new feature)