Added Connect Four Game in JS

[kiruba-r11]

Description

• The would-be 6 rows and 7 columns, and it's a two-player game.
• The first one to connect any four consecutive cells horizontally, vertically or diagonally, will be declared the winner.

Fixes #36

Type of change

Please delete options that are not relevant.

• This change requires a documentation update

Checklist:

• My code follows the style guidelines(Clean Code) of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests/screenshots(if any) that prove my fix is effective or that my feature works