Clarify MLflow catalog.yml file context in docs (#5389)

* Clarify MLflow catalog.yml file context in docs

Add `# conf/base/catalog.yml` comments to YAML code snippets in the MLflow integration docs to clarify where readers should place the configuration.

Closes #5384

Signed-off-by: Mridul Tailor <71081929+MridulTailor@users.noreply.github.com>

* Apply suggestion to delete intermediate blank line

Signed-off-by: Deepyaman Datta <deepyaman.datta@utexas.edu>

Signed-off-by: Deepyaman Datta <deepyaman.datta@utexas.edu>

* Add catalog.yml comment to model registry diff snippet

Signed-off-by: Mridul Tailor <71081929+MridulTailor@users.noreply.github.com>

---------

Signed-off-by: Mridul Tailor <71081929+MridulTailor@users.noreply.github.com>
Signed-off-by: Deepyaman Datta <deepyaman.datta@utexas.edu>
Co-authored-by: Deepyaman Datta <deepyaman.datta@utexas.edu>

Author: MridulTailor

docs/integrations-and-plugins/mlflow.md

@@ -142,7 +142,8 @@ For example, if you have a dataset corresponding to a scikit-learn model,
 you can change it as follows:
 
 ```diff
- regressor:
+# conf/base/catalog.yml
+regressor:
 -  type: pickle.PickleDataset
 -  filepath: data/06_models/regressor.pickle
 -  versioned: true
@@ -158,6 +159,7 @@ If you also want to _register_ it
 you can add a `registered_model_name` parameter:
 
 ```yaml
+# conf/base/catalog.yml
 regressor:
   type: kedro_mlflow.io.models.MlflowModelTrackingDataset
   flavor: mlflow.sklearn
@@ -173,6 +175,7 @@ To load a model from a specific run, you can specify the `run_id`.
 For that, you can make use of {ref}`runtime parameters <runtime-params>`:
 
 ```yaml
+# conf/base/catalog.yml
 # Add the intermediate datasets to run the inference pipeline
 X_test:
   type: pandas.ParquetDataset