PR template: Clarify compensation

Translators have been getting compensated for localization. Sometimes
they submit pull requests for their changes, but just because they do
doesn't mean that they won't get compensated.

The intent of this line was to make sure that any random contributor
wouldn't expect any compensation for their changes, so adding another
clause here still keeps that expectation while making it clear that it's
not like Terry _never_ compensates people. Even if, as a Swedish man
once sung, "Terry is a monster, I think we all know that".

.github/pull_request_template.md

@@ -34,4 +34,4 @@ By submitting this pull request, I confirm that...
 - [ ] My changes may be used in a future commercial release of VVVVVV
 - [ ] I will be credited in a `CONTRIBUTORS` file and the "GitHub Friends"
   section of the credits for all of said releases, but will NOT be compensated
-  for these changes
+  for these changes unless there is an agreement