docs: add about-us section in README.md

[hulxv]

Closes #4

[OmarShawky1]

Requested changes

1. The order of "About Us" is: Board of Leaders, Mentors, Curriculum Maintainers, Contributors. Please maintain same order.
2. Switch back all style changes. (Maybe do another PR with it if you want). you can save them locally using git stash if you are not familiar with git.

[hulxv]

Is there anything else should I do?

[OmarShawky1]

@hulxv
Excellent work. 2 things that can even make it more excellent.

1. In table, use |:-:| to center text in table. you don't need to use more than -.
2. Try to use logos from website instead of text.

If you don't want to do it, then this is fine and I will do it myself :)

[hulxv]

@OmarShawky1

[OmarShawky1]

Fixed in #4