Update 02-chapter_of_course.md

Removing links to a PDF that is no longer available in the docs > coursera > example chapter markdown

Author: kweav

docs/coursera/02-chapter_of_course.md

@@ -123,20 +123,6 @@ OR this works:
 
 <iframe src="https://www.youtube.com/embed/VOCYL-FNbr0" width="672" height="400px"></iframe>
 
-### Links to files
-
-This works:
-
-<iframe src="https://www.messiah.edu/download/downloads/id/921/Microaggressions_in_the_Classroom.pdf" width="672" height="800px"></iframe>
-
-Or this:
-
-[This works](https://www.messiah.edu/download/downloads/id/921/Microaggressions_in_the_Classroom.pdf).
-
-Or this:
-
-<iframe src="https://www.messiah.edu/download/downloads/id/921/Microaggressions_in_the_Classroom.pdf" width="672" height="800px"></iframe>
-
 ### Links to websites
 
 Examples of including a website link.