Removed Output to a file docs section (#4421)

Signed-off-by: Elena Khaustova <[email protected]>

docs/source/nodes_and_pipelines/run_a_pipeline.md

@@ -233,99 +233,6 @@ Out[11]: {'v': 0.666666666666667}
 </details>
 
 
-
-## Output to a file
-
-We can also use IO to save outputs to a file. In this example, we define a custom `LambdaDataset` that would serialise the output to a file locally:
-
-```{warning}
-`LambdaDataset` has been deprecated and will be removed in Kedro `0.20.0`.
-```
-
-<details>
-<summary><b>Click to expand</b></summary>
-
-
-```python
-def save(value):
-    with open("./data/07_model_output/variance.pickle", "wb") as f:
-        pickle.dump(value, f)
-
-
-def load():
-    with open("./data/07_model_output/variance.pickle", "rb") as f:
-        return pickle.load(f)
-
-
-pickler = LambdaDataset(load=load, save=save)
-io.add("v", pickler)
-```
-</details>
-
-It is important to make sure that the data catalog variable name `v` matches the name `v` in the pipeline definition.
-
-Next we can confirm that this `LambdaDataset` behaves correctly:
-
-<details>
-<summary><b>Click to expand</b></summary>
-
-```python
-io.save("v", 5)
-```
-
-```python
-io.load("v")
-```
-
-`Ouput`:
-
-```Console
-Out[12]: 5
-```
-</details>
-
-Finally, let's run the pipeline again now and serialise the output:
-
-<details>
-<summary><b>Click to expand</b></summary>
-
-
-```python
-SequentialRunner().run(pipeline, catalog=io)
-```
-
-`Ouput`:
-
-```console
-Out[13]: {}
-```
-</details>
-
-The output has been persisted to a local file so we don't see it directly, but it can be retrieved from the catalog:
-
-<details>
-<summary><b>Click to expand</b></summary>
-
-
-```python
-io.load("v")
-```
-
-`Ouput`:
-
-```console
-Out[14]: 0.666666666666667
-```
-
-```python
-try:
-    os.remove("./data/07_model_output/variance.pickle")
-except FileNotFoundError:
-    pass
-```
-</details>
-
-
 ## Configure `kedro run` arguments
 
 The [Kedro CLI documentation](../development/commands_reference.md#run-the-project) lists the available CLI options for `kedro run`. You can alternatively supply a configuration file that contains the arguments to `kedro run`.