Fix broken links due to capitalization in recent docs

[jessetylermullins]

Example: .../master/leadership.md does not work but .../master/Leadership.md does.

[cheapwebmonkey]

Let’s please keep all file and folder names lowercase. My bad for not catching this earlier

[jessetylermullins]

@cheapwebmonkey No worries! I created an issue on the main repo to address this in the contributions guidelines doc that we need to build.