update How to Design Programs textbook link

Author: spamegg1

README.md

@@ -160,11 +160,9 @@ All coursework under Core CS is **required**, unless otherwise indicated.
 `Ruby`
 `and more`
 
-The How to Code courses are based on the textbook [How to Design Programs](https://htdp.org/2003-09-26/). The First Edition is available for free online and includes problem sets and solutions. Students are encouraged to do these assignments.
-
 Courses | Duration | Effort | Prerequisites | Discussion
 :-- | :--: | :--: | :--: | :--:
-[How to Code - Simple Data](https://www.edx.org/course/how-to-code-simple-data) | 7 weeks | 8-10 hours/week | none | [chat](https://discord.gg/RfqAmGJ)
+[How to Code - Simple Data](https://www.edx.org/course/how-to-code-simple-data) [(textbook)](https://htdp.org/2022-8-7/Book/index.html) | 7 weeks | 8-10 hours/week | none | [chat](https://discord.gg/RfqAmGJ)
 [How to Code - Complex Data](https://www.edx.org/course/how-to-code-complex-data) | 6 weeks | 8-10 hours/week | How to Code: Simple Data | [chat](https://discord.gg/kczJzpm)
 [Programming Languages, Part A](https://www.coursera.org/learn/programming-languages) | 5 weeks | 4-8 hours/week | How to Code ([Hear instructor](https://www.coursera.org/lecture/programming-languages/recommended-background-k1yuh)) | [chat](https://discord.gg/8BkJtXN)
 [Programming Languages, Part B](https://www.coursera.org/learn/programming-languages-part-b) | 3 weeks | 4-8 hours/week | Programming Languages, Part A | [chat](https://discord.gg/EeA7VR9)