Add notes on the Arithmetic and Assignment Operators

[MartyOfMCA]

The feature to add
There really isn't explanation on the various arithmetic and assignment operators. I know they may be pretty straightforward but adding some explanation and sample code snipetts would be a wonderful learning experience for everyone learning from this repo.

• Provide brief explanation on the various arithmetic and assignment operators.
• Provide sample code snippets on each of these operators (completely optional)

I believe adding these will help everyone!