chore: documentation (#76)

* chore: update docstring example to use python code block

* docs: add documentation

* feat: add docs build + fix other workdlows

* fix: add missing return type

docs/reference/fixtures.md

@@ -0,0 +1,31 @@
+# `fixtures`
+
+Here's the reference for the fixture registry, enums, and loading utilities.
+
+You can import them directly from `fastapi_toolsets.fixtures`:
+
+```python
+from fastapi_toolsets.fixtures import (
+    Context,
+    LoadStrategy,
+    Fixture,
+    FixtureRegistry,
+    load_fixtures,
+    load_fixtures_by_context,
+    get_obj_by_attr,
+)
+```
+
+## ::: fastapi_toolsets.fixtures.enum.Context
+
+## ::: fastapi_toolsets.fixtures.enum.LoadStrategy
+
+## ::: fastapi_toolsets.fixtures.registry.Fixture
+
+## ::: fastapi_toolsets.fixtures.registry.FixtureRegistry
+
+## ::: fastapi_toolsets.fixtures.utils.load_fixtures
+
+## ::: fastapi_toolsets.fixtures.utils.load_fixtures_by_context
+
+## ::: fastapi_toolsets.fixtures.utils.get_obj_by_attr