update pull request template

Author: gonzalocasas

.github/pull_request_template.md

@@ -13,7 +13,7 @@
 
 _Put an `x` in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code._
 
-- [ ] I added a line to the `CHANGELOG.rst` file in the `Unreleased` section under the most fitting heading (e.g. `Added`, `Changed`, `Removed`).
+- [ ] I added a line to the `CHANGELOG.md` file in the `Unreleased` section under the most fitting heading (e.g. `Added`, `Changed`, `Removed`).
 - [ ] I ran all tests on my computer and it's all green (i.e. `invoke test`).
 - [ ] I ran lint on my computer and there are no errors (i.e. `invoke lint`).
 - [ ] I added new functions/classes and made them available on a second-level import, e.g. `compas_fab.robots.CollisionMesh`.