Add integration quality scale docs (#2457)

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>
Co-authored-by: Franck Nijhof <frenck@frenck.nl>
Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>

docs/core/integration-quality-scale/rules/docs-use-cases.md

@@ -0,0 +1,21 @@
+---
+title: "The documentation describes use cases to illustrate how this integration can be used"
+---
+
+## Reasoning
+
+Sometimes, seeing a device or service integrated into Home Assistant can make you wonder, "Why would I integrate this?"
+For some integrations, the intended use and benefit are more obvious than for others.
+
+Use case examples in the documentation can showcase the value of an integration.
+
+## Example implementation
+
+```markdown showLineNumbers
+The motion detection devices of MyCompany are cheap and usable.
+When you combine it with their other device you can do x.
+```
+
+## Exceptions
+
+There are no exceptions to this rule.