Add new algorithm (Interpolation Search).

[rioooxd]

PR Checklist:

• [X] My submission is formatted according to the guidelines in the contributing guide
• [X] My addition is on refer on the language README.md file
• [X] My addition does not have a spelling problem
• [X] My submission has a proper and user-friendly description of the algorithm
• [X] My submission has the time complexity of the algorithm
• [X] My submission has sample input-output of the program (NOT FOR PYTHON)

What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [X] New algorithm
• [ ] Optimization in previous algorithms
• [ ] Code style update
• [ ] Refactor
• [X] Documentation
• [ ] Other, please describe:

Briefly describe the changes in this PR

I added new algorithm called Interpolation search in C#. https://www.youtube.com/watch?v=YSVS5GG1JuI

Other information: It's my first commit to non tutorial repository so please be understanding

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