Add pointer to tech contrib doc in PR template

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,4 +1,3 @@
 NOTICE: Are you attempting to submit a lesson to the Programming Historian? We no longer accept lesson submissions by pull request to this repository. Please consult our [guidelines for submitting a lesson](http://programminghistorian.org/new-lesson-workflow) for further instructions.
 
-If your pull request instead concerns some issue with the formatting or functioning of our site, or some error in an existing lesson, feel free to proceed with your PR and delete this template text!
-
+If your pull request instead concerns some issue with the formatting or functioning of our site, or some error in an existing lesson, please see our technical contribution guidelines: https://github.com/programminghistorian/jekyll/wiki/Making-technical-contributions