docs: add how-to docs (#739)

* add how-to docs

* Apply suggestions from code review

Co-authored-by: Erin Conley <erin.conley@canonical.com>

---------

Co-authored-by: Erin Conley <erin.conley@canonical.com>

Author: cbartz

docs/changelog.md

@@ -2,6 +2,10 @@
 
 This changelog documents user-relevant changes to the GitHub runner charm.
 
+## 2026-02-25
+
+- Add the  `How to upgrade` documentation.
+
 ## 2026-02-12
 
 - Add support to integrate with GitHub Runner planner charm with the `github_runner_planner_v0` interface.

docs/how-to/upgrade.md

@@ -0,0 +1,9 @@
+# Upgrade
+
+In order to upgrade the charm, refresh the revision using the `juju refresh` command:
+
+```bash
+juju refresh github-runner
+```
+
+Verify if the charm is active and idle by running the `juju status --wait 1s` command.

docs/index.md

@@ -59,6 +59,7 @@ Thinking about using the GitHub runner charm for your next project? [Get in touc
   1. [Spawn OpenStack runner](how-to/openstack-runner.md)
   1. [Set up reactive spawning](how-to/reactive.md)
   1. [Comply with security requirements](how-to/comply-security.md)
+  1.  [Upgrade](how-to/upgrade.md)
   1. [Contribute](how-to/contribute.md)
 1. [Reference](reference)
   1. [Actions](reference/actions.md)