docs: 📝 expand on CONTRIBUTING guide (#2)

Author: lwjohnst86

CONTRIBUTING.md

@@ -1,6 +1,51 @@
-# Want to contribute? Great! :tada:
+# Contributing
 
-Check out the [Contributing
-Guide](https://guides.rostools.org/contributing) for more details on how
-to contribute. As always, make sure to adhere to the [Code of
-Conduct](CODE_OF_CONDUCT.md).
+## Issues and bugs :bug:
+
+The easiest way to contribute is to report issues or bugs that you might
+find while using `template-workshop`. You can do this by creating a
+[new](https://github.com/rostools/template-workshop/issues/new/choose)
+issue on our GitHub repository.
+
+## Adding or modifying content :pencil2:
+
+If you would like to contribute content, please check out our
+[guide](https://guides.rostools.org/contributing) for more specific
+details on how we work and develop. It is a regularly evolving document,
+so is at various states of completion.
+
+To contribute to `template-workshop`, you first need to install
+[uv](https://docs.astral.sh/uv/) and
+[justfile](https://just.systems/man/en/packages.html). We use uv and
+justfile to manage our project, such as to run checks and test the
+template. Both the uv and justfile websites have a more detailed guide
+on using uv, but below are some simple instructions to get you started.
+
+It's easiest to install uv and justfile using
+[pipx](https://pypa.github.io/pipx/), so you should install that first.
+Then, to install uv and justfile, run:
+
+``` bash
+pipx install uv rust-just
+```
+
+We keep all our development workflows in the `justfile`, so you can
+explore it to see what commands are available. To see a list of commands
+available, run:
+
+``` bash
+just
+```
+
+As you contribute, make sure your changes will pass our tests by opening
+a terminal so that the working directory is the root of this project
+(`template-workshop/`) and running:
+
+``` bash
+just run-all
+```
+
+When testing the template, copier can only use content kept in the Git
+history. Meaning that if you make changes to the template and try to
+test it, it won't be able to test those changes. You have to commit the
+changes first in order for copier to use them.