Added fibonacci.cpp

[atiwari1504]

[CorruptComputer]

Wrong repo and format of PR.

Excerpt from: https://github.com/karan/Projects/blob/master/CONTRIBUTING.md

Solutions

Please do not send pull requests for replacing my code. If you'd like to contribute solutions, please see the following instructions:

• Solve the problem, and keep it in your repo. DO NOT send merge request yet.

• Find the problem in this README file.

• Edit the file in this format (notice the double square brackets):

• This is a problem - And here goes it's description. [octocat (language)] [your_username (C++)]

• This results in something like this:

• This is a problem - And here goes it's description. [octocat (language)] [your_username (C++)]

• Please respect other people and do not delete or move anyone else's link. Place your solution at the end of the list of solutions.

• Save/Commit the README.md file.

• Send a pull request for this commit ONLY - ie, the commit to the solutions repo!