Some advice to a format README

[TravorLZH]

README created by @malhotra5 explains everything carefully about the tutorial of manim. However I believe there are still methods to let README both look better and be synchronized to manim's update:

1. Formatting: There are many syntax in markdown to express different types of content, and I suggest that we could adopt those other syntaxes in README
2. Outdated parts: There is no need to obtain manim's repository now because it is made available to pip interface, so we really should change these.
3. More information can be added to README: After reading its the source code, I have more understanding in manim's process of creating animations.

By the way, I also request assigning this issue to myself since I have already started working on the solutions in my fork of this repo.

[TravorLZH]

Because I am developing these on a Mac, I can also put guide for installing manim on a computer running OSX