chore: update contributing documentation

Update the contributing guide with information related to using
tox.

Signed-off-by: Billy Olsen <[email protected]>

CONTRIBUTING.md

@@ -1,34 +1,67 @@
-# lldpd
+# Contributing to the lldpd charm
+
+## Overview
+
+This document explains the processes and practices recommended for contributing enhancements to
+this charm.
+
+- Generally, before developing enhancements to this charm you should consider [opening an issue](
+  https://github.com/canonical/charm-lldp/issues) explaining your bug or use case.
+- Familiarising yourself with the [Charmed Operator Framework](https://juju.is/docs/sdk)
+  library will help you when working on new features or bug fixes.
+- All enhancements and code changes require review before being merged. Code review typically
+  examines:
+  - code quality
+  - test coverage
+  - user experience for administrators deploying and operating this charm
+- Please help us out by ensuring easy to review branches by rebasing your pull request branch
+  onto the `main` branch. This also avoids merge commits and creates a linear Git commit
+  history. Please do *not* merge the main branch into your PR.
 
 ## Developing
 
-Create and activate a virtualenv with the development requirements:
+Install `tox`, `charmcraft` and `juju`.
 
-    virtualenv -p python3 venv
-    source venv/bin/activate
-    pip install -r requirements-dev.txt
+```bash
+sudo apt-get install tox
+sudo snap install charmcraft --classic
+sudo snap install juju
+```
 
-## Code overview
+## Testing
 
-TEMPLATE-TODO:
-One of the most important things a consumer of your charm (or library)
-needs to know is what set of functionality it provides. Which categories
-does it fit into? Which events do you listen to? Which libraries do you
-consume? Which ones do you export and how are they used?
+To test the charm, there are several tox targets which can be used
 
-## Intended use case
+```commandline
+tox run -e format       # update your code according to linting rules
+tox run -e lint         # code style tests
+tox run -e static-charm # runs static analysis on the charm
+tox run -e unit         # unit tests
+tox                     # runs lint, static analysis and unit tests
+```
 
-TEMPLATE-TODO:
-Why were these decisions made? What's the scope of your charm?
+## Building
 
-## Roadmap
+Build the charm in the local repository using the `charmcraft` tool.
 
-If this Charm doesn't fulfill all of the initial functionality you were
-hoping for or planning on, please add a Roadmap or TODO here
+```commandline
+charmcraft pack
+```
 
-## Testing
+## Deploy
+
+```commandline
+# Create a model
+juju add-model test
+
+# Enable debug logging (optional)
+juju model-config logging-config="<root>=INFO;unit=DEBUG"
 
-The Python operator framework includes a very nice harness for testing
-operator behaviour without full deployment. Just `run_tests`:
+# Deploy the charm
+juju deploy --base [email protected] ./lldpd_ubuntu-22.04-amd64.charm
+```
 
-    ./run_tests
+## Canonical Contributor Agreement
+Canonical welcomes contributions to the lldpd charm. Please check out our [contributor 
+agreement](https://ubuntu.com/legal/contributors) if you are interested in contributing to this
+code base.