PR template: Clarification

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,5 +1,7 @@
 <!--
 **Note:** Pull Requests should be made against the `master` by default.
 
-Only make Pull Requests against other branches (e.g. `2.1` or `3.0`) if your changes only apply to that specific version of Godot.
+Only make Pull Requests against other branches (e.g. `2.1`) if your changes only apply to that specific version of Godot.
+
+All pull requests for Godot 3 should usually go into `master`.
 -->