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/async-dependency.md

@@ -0,0 +1,25 @@
+---
+title: "Dependency is async"
+related_rules:
+  - inject-websession
+---
+import RelatedRules from './_includes/related_rules.jsx'
+
+## Reasoning
+
+Home Assistant works with asyncio to be efficient when handling tasks.
+To avoid switching context between the asyncio event loop and other threads, which is costly performance wise, ideally, your library should also use asyncio.
+
+This results not only in a more efficient system but the code is also more neat.
+
+## Additional resources
+
+More information on how to create a library can be found in the [documentation](../../../api_lib_index).
+
+## Exceptions
+
+There are no exceptions to this rule.
+
+## Related rules
+
+<RelatedRules relatedRules={frontMatter.related_rules}></RelatedRules>