docs: add deprecated tag

Author: RealKai42

articles/machine-learning/component-reference/feature-hashing.md

@@ -1,7 +1,7 @@
 ---
 title: "Feature Hashing component reference"
 titleSuffix: Azure Machine Learning
-description: Learn how to use the Feature Hashing component in the Azure Machine Learning designer to featurize text data.
+description: [Deprecated] Learn how to use the Feature Hashing component in the Azure Machine Learning designer to featurize text data.
 services: machine-learning
 ms.service: azure-machine-learning
 ms.subservice: core

articles/machine-learning/component-reference/pca-based-anomaly-detection.md

@@ -1,7 +1,7 @@
 ---
 title: "PCA-Based Anomaly Detection: Component reference"
 titleSuffix: Azure Machine Learning
-description: Learn how to use the PCA-Based Anomaly Detection component to create an anomaly detection model based on principal component analysis (PCA).
+description: [Deprecated] Learn how to use the PCA-Based Anomaly Detection component to create an anomaly detection model based on principal component analysis (PCA).
 services: machine-learning
 ms.service: azure-machine-learning
 ms.subservice: core

articles/machine-learning/component-reference/poisson-regression.md

@@ -1,7 +1,7 @@
 ---
 title: "Poisson Regression: Component reference"
 titleSuffix: Azure Machine Learning
-description: Learn how to use the Poisson Regression component in Azure Machine Learning designer to create a Poisson regression model.
+description: [Deprecated] Learn how to use the Poisson Regression component in Azure Machine Learning designer to create a Poisson regression model.
 services: machine-learning
 ms.service: azure-machine-learning
 ms.subservice: core