Add section for Editorials.

#### This issue is about [Problem](problem_link) from [Contest](contest_link).

- [ ] Issue Title is in form `Problem Code (Contest Code) [Language]`
- [ ] I have a better solution for this problem.
- [ ] I ensure I'm Eligible as per [ECR](https://github.com/aashutoshrathi/ChefLib/blob/master/README.md#ecr).
- [ ] I got AC for this problem when contest was live. (Not necessary, but appreciable).
- [ ] I have checked that my solution is passing on Problem (in case you make some changes).
- [ ] I will send my PR only after I'm assigned to this issue by any maintainer.
- [ ] 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 upon what is required once you open an issue.

No file, test, or entry point is named; first clarify where the Editorials section belongs and what content or format it should contain. Done means the requested Editorials section is added with its placement and expected contents agreed by the maintainer.

Written by the indexing model from the issue text.