Extend singleton and provided instance docs

docs/providers/provided_instance.md

@@ -1,3 +1,46 @@
 # Provided instance
 
-soon...
+You can pass provider field values to other providers,
+which will provide dependency injection.
+To access the values of an object's fields inside a provider,
+you need to use the `provided` property of the provider.
+
+This is useful in cases when your entities depend on external data
+from configuration files or environment variables.
+You need to parse this external data and save it into a class or dataclass,
+and the container will inject this data.
+
+### Example
+```python3
+from dataclasses import dataclass
+
+from injection import DeclarativeContainer, providers
+
+
+@dataclass
+class Settings:
+    env_1: str
+    env_2: int
+
+
+class SomeService:
+    def __init__(self, env_1: str, env_2: int):
+        self.env_1 = env_1
+        self.env_2 = env_2
+
+
+class Container(DeclarativeContainer):
+    settings = providers.Singleton(Settings, env_1="value", env_2=193)
+
+    service = providers.Transient(
+        SomeService,
+        env_1=settings.provided.env_1,
+        env_2=settings.provided.env_2,
+    )
+
+
+if __name__ == "__main__":
+    resolved_service = Container.service()
+    assert resolved_service.env_1 == "value"
+    assert resolved_service.env_2 == 193
+```

docs/providers/singleton.md

@@ -3,7 +3,7 @@
 **Singleton** provider creates and returns a new object on the first call
 and caches it, and on subsequent calls it returns the cached object.
 
-## Example
+### Example
 
 ```python3
 from dataclasses import dataclass
@@ -28,3 +28,29 @@ if __name__ == "__main__":
     assert instance1.field == 15
 
 ```
+
+## Resetting memoized object
+
+To **reset a memorized object** you need to call the `reset` method of the Singleton provider.
+
+### Example
+
+```python3
+from injection import DeclarativeContainer, providers
+
+
+class SomeClass: ...
+
+
+if __name__ == "__main__":
+    provider = providers.Singleton(SomeClass)
+    obj = provider()
+    obj2 = provider()
+
+    assert obj is obj2
+    provider.reset()
+
+    obj3 = provider()
+    assert obj is not obj3
+    assert obj2 is not obj3
+```