implemented palindrome checking using c#

[gabrielhs1357]

This PR implements the code for Palindrome checking in C# referred in issue #161.

I have read the contributing guidelines in CONTRIBUTING.md and have ensured the following:

• My code is placed in the required directory as outlined in CONTRIBUTING.md
• My code file is named according to CONTRIBUTING.md
• Variables, classes, functions etc. follow camel case as outlined in CONTRIBUTING.md
• My code hasn't been implemented or claimed by someone else and I have checked the present issues and PRs for the same
• My code is well commented
• If my code is the first implementation of , I have added the link to this directory in README.md
• I have not copied my code from anywhere

[gabrielhs1357]

Hi guys! Sorry but I did not found the issue for this algo, this is why I'm not mentioning the issue number on the PR comment.

[codelixir]

My bad, I had closed #161 earlier. I have reopened it now, please comment on the issue and include the issue number in your PR description.

The code looks good to me; I'll merge the PR once you make these changes.

[gabrielhs1357]

My bad, I had closed #161 earlier. I have reopened it now, please comment on the issue and include the issue number in your PR description.

The code looks good to me; I'll merge the PR once you make these changes.

Done, thanks!