Added List Methods and updated TOC

[ombailey]

Change Summary

Provide summary of changes with issue number if any.

Checklist

If you haven't fulfilled the below requirements or even delete the entire checklist, your PR won't be reviewed and will be closed without notice.

General

• [ ] This Pull Request is all my own work. (You'll be blacklisted if you are caught for plagiarism.)
• [ ] I've read CONTRIBUTING.md
• [ ] I've made some valid changes to the CheatSheet, and they are not just minor changes.

Changes

• [ ] I've read and followed the Solution Template

[aryankashyap7]

@ombailey There are some conflicts with the existing changes, Try to resolve them. Even prefer adding more valuable information instead of small sections. Although your previous changes with Declaring Variables are accepted, A cheatsheet with a single section is never preferable.

[ombailey]

Ok no problem!