Added Programiz PRO that offers curated learning paths for beginners

[awalrujaa]

Description

• Introduced Programiz PRO in Additional Resources
• Programiz PRO offers curated learning paths that consist of interactive courses, challenge courses, and interview preparation courses with hands-on practice for learners.

  Motivation and Context

• Programiz PRO offers structured, in-depth learning materials from which beginners to intermediate learners can benefit.
• Programiz PRO's Community Challenges is a platform where you can solve a number of coding challenges for free.

How Has This Been Tested?

Types of changes

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

Checklist:

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

[awalrujaa]

@adilkhash @ashokgelal @kbariotis @bobeff Hey! Could you review this Pull Request?

[ashokgelal]

Lgtm