Add info about sorting algorithms to README.md

[diptangsu]

Add a few lines about every sorting algorithm present in the repository in the README.md file.

[ErwanLT]

how descriptive should be the algorithm description ?

[diptangsu]

Just a simple description will do. It's not for people who don't know anything about sorting algorithms. Copy paste from somewhere that makes sense.
It's simply something for people to read instead of going to the code directly.

[Gupta-Vandana]

is this issue still open ?

[diptangsu]

@vandanagupta1501 As long as you can add something good to it, it's open.