Add pull request template

.github/PULL_REQUEST_TEMPLATE/pull_request_template.md

@@ -0,0 +1,22 @@
+---
+name: Pull Request
+about: Propose a change to TiddlyWiki 5
+title: ""
+labels: ''
+assignees: ''
+
+---
+
+**Is your PR related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you are proposing**
+A clear and concise description of the changes you are proposing. Include images to show visual changes.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.
+
+If you link to discussions elsewhere then please copy and paste the important text, and don't expect readers to scan the entire discussion to find the relevant part.