Add Longest Word in C#

[alstondsouza1]

To request a new code snippet, please fill out the following:

Project name: Longest Word Project link: https://sampleprograms.io/projects/my-project-name Language: C#

If this code snippet will also be the first in a new language, please fill out the following:

Official Language Style Guide: Official Language Website: Official Language Docker Image: https://hub.docker.com/r/repository/image

The project link must be a link to a project on the Sample Programs Website project list. If you would like to add a new project to the Sample Programs Website, please first make a pull request to the Sample Programs Website.

[rzuckerm]

@alstondsouza1 Please check the existing issues before logging a new one. Please add a comment to #3319 , and I'll assign you

[alstondsouza1]

@rzuckerm Apologies, I'll double check that next time, thank you.