Replace Coursera courses or otherwise address that they're no longer free

[luccaflower]

In many cases the material is freely available elsewhere.

• Programming Languages ABC
• Software Architecture (is this even needed according to the curricular guidelines?)
• Entire Ethics section
• Secure Coding Practices
• Machine Learning
• Parallel Programming
• Game Theory
• Security Governance and Compliance
• Digital Forensics Concepts

[Flomza]

For security, I think a great resource we should add or take inspiration from is https://teachyourselfinfosec.com/
That covers much of the necessary security topics & more.

[pulkitkrishna00]

I have replaced links for PLABC, but still need to write a more detailed coursepage (that can be done later).