ML Docs: Update header description

Author: xhlu

doc/python/ml-knn.md

@@ -23,7 +23,7 @@ jupyter:
     version: 3.7.6
   plotly:
     description: Visualize scikit-learn's k-Nearest Neighbors (kNN) classification
-      with Plotly
+      in Python with Plotly.
     display_as: ai_ml
     language: python
     layout: base

doc/python/ml-pca.md

@@ -23,7 +23,7 @@ jupyter:
     version: 3.7.6
   plotly:
     description: Visualize Principle Component Analysis (PCA) of your high-dimensional
-      data with Plotly on Python.
+      data in Python with Plotly.
     display_as: ai_ml
     language: python
     layout: base

doc/python/ml-roc-pr.md

@@ -23,7 +23,7 @@ jupyter:
     version: 3.7.6
   plotly:
     description: Interpret the results of your classification using Receiver Operating
-      Characteristics (ROC) and Precision-Recall (PR) Curves using Plotly on Python.
+      Characteristics (ROC) and Precision-Recall (PR) Curves in Python with Plotly.
     display_as: ai_ml
     language: python
     layout: base