Add Readme for October Long Contest

[manish1997]

• [ ] Issue Title is in form Problem Code (Contest Code) [Language]
• [ ] I ensure I'm Eligible as per ECR.
• [ ] I got AC for this problem when the contest was live. (Not necessary, but appreciable).
• [ ] I have checked that my solution is passing on Problem (in case you make some changes).
• [x] I will send my PR only after I'm assigned to this issue by any maintainer.
• [x] I ensure that I'm not assigned to more than 2 issues.
  • [x] Assign this issue to me (I want to work on this).

It's not necessary for all for points to be checked, we will look at what is required once you open an issue.

[manish1997]

@aashutoshrathi assign this to me :)