Update README.md

[rohitjmathew]

Add more descriptions to follow:

• Make an issue before implementing a solution
• Add documentation of the implementation in the README.md (Could look at discussing better ways to frame this)

[AkashM398]

@rohitjmathew I hope this is already mentioned in CONTRIBUTING.md

[AkashM398]

@rohitjmathew you can work on this issue as said, will look into it.