Update links to MARS Simulator (#285)

docs/INSTALLATION.md

@@ -1,3 +1,3 @@
 # Installation
 
-For these problems, we use the popular MIPS simulator [MARS](http://courses.missouristate.edu/KenVollmar/mars/). Download the MARS jar archive from the MARS website and place it somewhere easily accessible. Also install the Java SDK if you do not have it already.
+For these problems, we use the popular MIPS simulator [MARS](https://dpetersanderson.github.io/Help/MarsHelpIntro.html). Download the MARS jar archive from [GitHub](https://github.com/dpetersanderson/MARS/releases) and place it somewhere easily accessible. Also install the Java SDK if you do not have it already.

docs/RESOURCES.md

@@ -1,9 +1,9 @@
 # Resources
 
 
-* [MIPS Green Sheet](https://inst.eecs.berkeley.edu/~cs61c/resources/MIPS_Green_Sheet.pdf)
+* [MIPS Green Sheet](https://courses.cs.washington.edu/courses/cse378/09au/MIPS_Green_Sheet.pdf)
 * [cburch reference card](http://www.cburch.com/cs/330/reading/mips-ref.pdf)
 * [MIPS Instruction Reference](https://mathcs.holycross.edu/~csci226/MIPS/MIPS_InstructionReference.html)
 * [MIPS Instruction Set Cheat Sheet](https://group.miletic.net/en/teaching/materials/mips-instruction-set/)
 * [MIPS syntax vim plugin](https://github.com/harenome/vim-mipssyntax)
-* [Writing and Using Macros](https://courses.missouristate.edu/kenvollmar/mars/help/MacrosHelp.html)
+* [Writing and Using Macros](https://dpetersanderson.github.io/Help/MacrosHelp.html)