Add pull request template (#2402)

* Add pull request template

* Put comments on single line and Add additional info section

* Change "here" to "below"

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,28 @@
+## Checklist
+
+<!-- Put an `x` in all the boxes that apply -->
+
+- [ ] I read and understood the **[Contributing Guidelines](https://github.com/JustArchiNET/ArchiSteamFarm/blob/main/.github/CONTRIBUTING.md)**.
+- [ ] This is not a **[duplicate](https://github.com/JustArchiNET/ArchiSteamFarm/pulls)** of an existing merge request.
+- [ ] I believe this falls into the scope of the project and should be part of the built-in functionality.
+- [ ] My code follows the **[code style](https://github.com/JustArchiNET/ArchiSteamFarm/blob/main/.github/CONTRIBUTING.md#code-style)** of this project.
+- [ ] I have added tests to cover my changes, wherever they are necessary.
+- [ ] All new and existing tests pass.
+
+## Changes
+
+### New functionality
+
+<!-- Please describe below, what new functionality was added. -->
+
+### Changed functionality
+
+<!-- Please describe below, what old functionality was changed. -->
+
+### Removed functionality
+
+<!-- Please describe below, what old functionality was removed. Make sure to mention what it was replaced with or how everything that was previously achievable still is. -->
+
+## Additional info
+
+<!-- Everything else you consider note-worthy that we didn't ask for. -->