docs: add changelog (ISD-2719) (#647)

* docs: add changelog

* Update .github/pull_request_template.md

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

---------

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

Author: amandahla

.github/pull_request_template.md

@@ -33,5 +33,6 @@ Please, provide some information about your PR before proceeding.
 - [ ] The documentation is generated using `src-docs`
 - [ ] The documentation for charmhub is updated.
 - [ ] The PR is tagged with appropriate label (`urgent`, `trivial`, `complex`)
+- [ ] The changelog is updated with changes that affect the users of the charm.
 
 <!-- Explanation for any unchecked items above -->

docs/changelog.md

@@ -0,0 +1,5 @@
+# Changelog
+
+### 2025-01-09
+
+- Add changelog for tracking user-relevant changes.

docs/how-to/contribute.md

@@ -63,6 +63,12 @@ Run the following command:
 echo -e "tox -e src-docs\ngit add src-docs\n" >> .git/hooks/pre-commit
 chmod +x .git/hooks/pre-commit
 ```
+### Changelog
+
+Please ensure that any new feature, fix, or significant change is documented by
+adding an entry to the `docs/changelog.md` file.
+
+To learn more about changelog best practices, visit [Keep a Changelog](https://keepachangelog.com/).
 
 ## Build charm