Update readme file for all directories

[Cgarg9]

Readme files have to be consistent throughout the repo in every directory.

Follow structure as specified in the clustering folder.

It should contain -

• a small intro to the directory
• structure
• learning flow - contains algo name, learning resources, topics covered
• assignments
• Getting started

[guntaaskapoor24]

@Cgarg9 can I please be assigned this issue?

[Cgarg9]

Sure.
Please go through the readme of the clustering folder and follow that structure. You'll need to update all the directories for me to merge the PR and please go through the notebooks so you only mention topics that are covered.