Add testing rule to contribution guidelines (#56147)

Adds a clause to the contributing guidelines that you are expected to have tested your code, which implicitly bans webedited larger PRs. Also updates the wording about changelogs.

.github/CONTRIBUTING.md

@@ -557,9 +557,11 @@ There is no strict process when it comes to merging pull requests. Pull requests
 
 * Make sure your pull request complies to the requirements outlined here
 
+* You are expected to have tested your pull requests if it is anything that would warrant testing. Text only changes, single number balance changes, and similar generally don't need testing, but anything else does. This means by extension web edits are disallowed for larger changes.
+
 * You are going to be expected to document all your changes in the pull request. Failing to do so will mean delaying it as we will have to question why you made the change. On the other hand, you can speed up the process by making the pull request readable and easy to understand, with diagrams or before/after data. Should you be optimizing a routine you must provide proof by way of profiling that your changes are faster.
 
-* We ask that you use the changelog system to document your change, which prevents our players from being caught unaware by changes - you can find more information about this [on this wiki page](http://tgstation13.org/wiki/Guide_to_Changelogs).
+* We ask that you use the changelog system to document your player facing changes, which prevents our players from being caught unaware by said changes - you can find more information about this [on this wiki page](http://tgstation13.org/wiki/Guide_to_Changelogs).
 
 * If you are proposing multiple changes, which change many different aspects of the code, you are expected to section them off into different pull requests in order to make it easier to review them and to deny/accept the changes that are deemed acceptable.