Shell Sort in C++

[Akashsingh310]

I wish to add the shell sort algorithm in C++.

[stale]

It will be now be reviewed manually. Thanks for contributions. If you have more concerns, you may get the conversation started at our discord server

[Akashsingh310]

Adds the shell sort algorithm written in C++
Fixes #192

[stale]

It will be now be reviewed manually. Thanks for contributions. If you have more concerns, you may get the conversation started at our discord server