Updates C tutorials

[johnoro]

Description

Updates C Project Based Tutorials to link to https://github.com/rby90/Project-Based-Tutorials-in-C instead of https://www.reddit.com/r/C_Programming/comments/872rlt/c_project_based_tutorials

Motivation and Context

If you read through the Reddit thread, the new GitHub link is more up to date.

How Has This Been Tested?

I've looked through both links and compared the resource lists. The GitHub repository has the same resources and then some more.

Types of changes

• Content Update (change which fixes an issue or updates an already existing submission)
• New Article (change which adds functionality)
• Documentation change

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have made checks to ensure URLs and other resources are valid