docs: add contributing, support, and issues sections

This is to it make it very clear how to contribute, get support, or raise an
issue, which are requirements for JOSS.

README.md

@@ -35,6 +35,9 @@ OpenTTDLab is based on [Patric Stout's OpenTTD Savegame Reader](https://github.c
   - [Downloading from BaNaNaS](#downloading-from-bananas)
 - [Tips for repeatability, reproducibility, and replicability](#tips-for-repeatability-reproducibility-and-replicability)
 - [Compatibility](#compatibility)
+- [How to contribute](#how-to-contribute)
+- [How to report an issue](#how-to-report-an-issue)
+- [How to get help](#how-to-get-help)
 - [How to cite OpenTTDLab](#how-to-cite-openttdlab)
 - [Licenses and attributions](#licenses-and-attributions)
 
@@ -351,6 +354,23 @@ This is arguably the most difficult of the 3Rs to plan for, and for other resear
 - Python >= 3.8.0 (tested on 3.8.0 and 3.12.0)
 
 
+## How to contribute
+
+Contributions to OpenTTDLab are welcome - see [GitHub's guide on how to contribute to projects through pull requests](https://docs.github.com/en/get-started/exploring-projects-on-github/contributing-to-a-project).
+
+However, if there is no existing [issue](https://github.com/michalc/OpenTTDLab/issues) that you're addressing with your contribution, in most cases it's better to start a [discussion](https://github.com/michalc/OpenTTDLab/discussions) before raising a pull request. However, this is not a requirement, and probably unnecessary for small or no-brainer improvements.
+
+
+## How to report an issue
+
+To report an report an issue with OpenTTDLab, please use [GitHub issues](https://github.com/michalc/OpenTTDLab/issues).
+
+
+## How to get help
+
+If you would like help using OpenTTDLab, please ask a question in [GitHub discussions](https://github.com/michalc/OpenTTDLab/discussions).
+
+
 ## How to cite OpenTTDLab
 
 If you use OpenTTDLab in a scientific publication, a citation to the dissertation for which it was developed, [A Reusable Python Framework for Repeatable, Replicable, & Reproducible Experiments Using OpenTTD](https://doi.org/10.7488/era/5414), is appreciated.