Add better link for How to Code courses

[pulkitkrishna00]

Add the Systematic Program Design course (which consists of both parts of How to Code) as the main link and move How to Code to alt.

This version of the course does not seem to expire and has access to the questions, which are under paywall in the current linked course. While you cannot submit the solution to the questions, you can see them and see answers by clicking on "Show answers".

Related discord messages: 1, 2

Since the course material is the exact same, I do not think this change is major enough to need an RFC, but if it is needed, I will open one.

[waciumawanjohi]

1. Very interesting find. Thanks for identifying. And for providing supporting links.
2. I think its worth keeping the alt as the book site. It presents the material in a different modality rather than the same lectures on the same platform. Willing to switch that back?
3. I am a little concerned about the fact that this course doesn't have a front page.
   1. Systemic Program Design:
      
   2. HtC:
      
      But feedback (questions that you can answer and check) is more important.

[pulkitkrishna00]

I think its worth keeping the alt as the book site. It presents the material in a different modality rather than the same lectures on the same platform. Willing to switch that back?

I did not want to remove it, just forgot about it. Added it back.

I am a little concerned about the fact that this course doesn't have a front page.

Yes, I am also concerned about this. It may confuse some people, but as you said it also brings many improvements which are more important.