Ensure there is only a single top-level heading per page. (#67)

* fix h1 in extra courses

* fix h1 in cbpd

* fix h1 in contributing

* fix h1 in precollege-math extras

Author: ada-0x1eaf

docs/computer-science/extras/courses.md

@@ -103,7 +103,7 @@ Courses | Duration | Effort
 [How to Use Git and GitHub](https://www.udacity.com/blog/2015/06/a-beginners-git-github-tutorial.html) | 3 weeks | 2-3 hours/week
 [Kubernetes Certified Application Developer](https://www.udemy.com/course/certified-kubernetes-application-developer/) | 5 weeks | 2 hours/week
 
-# Online Learning - Great Courses
+## Online Learning - Great Courses
 
 Courses | Duration | Effort
 :-- | :--: | :--:

docs/computer-science/program-design/class-based/index.md

@@ -14,7 +14,7 @@ Starting from Assignment 3, the homework scales massively. It is believed to be
 
 Note that the video that goes with lecture 30 is inaccessable, watch [this video](https://www.youtube.com/watch?v=6WZo7sFFFlQ&list=PL_N7YxtCMPyea2YC3e-1s7SR_S3oWGjdb) instead. *Credit: @nadi726, Discord*
 
-# Course Syllabus
+## Course Syllabus
 To make it easier on students, a syllabus was created to give a general sequence that the lectures & assignments should be taken.
 *Credit: @nadi726, Discord*
 

docs/contributing.md

@@ -27,6 +27,6 @@ Issues require more than just users to suggest them. Issues require active commu
 
 Learning is enhanced by engaged peers. You can be that peer for someone new to the Borr Project. When you see a new person posting in Discord, ask them a question about themselves. When you see a cohort starting at _almost_ the right time, join in. Doing so will make the Borr Project a stronger program for everyone, including you.
 
-# Personal Customization
+## Personal Customization
 
-If you want to customize the curriculum for yourself, you are encouraged to [fork this project](https://help.github.com/articles/fork-a-repo/)!
+If you want to customize the curriculum for yourself, you are encouraged to [fork this project](https://help.github.com/articles/fork-a-repo/)!

docs/precollege-math/extras/courses.md

@@ -49,7 +49,7 @@ Courses | Duration | Effort
 [Professor Leonard Precalculus](https://www.youtube.com/playlist?list=PLDesaqWTN6ESsmwELdrzhcGiRhk5DjwLP) | - | -
 
 
-# Online Learning - Great Courses
+## Online Learning - Great Courses
 
 Courses | Duration | Effort
 :-- | :--: | :--: