feat: adds lesson_21 homework and lesson_22 pre-work (#542)

Signed-off-by: Anthony D. Mays <[email protected]>

Author: anthonydmays

lesson_21/README.md

@@ -9,4 +9,7 @@ Please review the following resources before lecture:
 
 ## Homework
 
-- TODO(anthonydmays): Figure this out
+- [ ] Complete [Project OOP Team Member Surveys][survey-link] (for each team member).
+- [ ] Do pre-work for [lesson 22](/lesson_22/).
+
+[survey-link]: https://forms.gle/VtPkEUYT1fh6B82D8

lesson_22/README.md

@@ -0,0 +1,17 @@
+# Lesson 22: Building Applications ([Slides](https://code-differently.github.io/code-differently-25-q1/slides/#/lesson_22))
+
+## Pre-work
+
+Please review the following resources before lecture:
+
+### Required
+* [Frontend web development - a complete overview (Video)](https://www.youtube.com/watch?v=WG5ikvJ2TKA)
+* [Backend web development - a complete overview (Video)](https://www.youtube.com/watch?v=XBu54nfzxAQ)
+* [3 Tier Architecture (Video)](https://www.youtube.com/watch?v=THPg8Hz2zZo)
+
+### Recommended
+* [What is an API (in 5 minutes) (Video)](https://www.youtube.com/watch?v=ByGJQzlzxQg)
+
+## Homework
+
+- TODO(anthonydmays): Provide more details