Update index.md

I have made changes as mentioned in the issue.

contrib/machine-learning/index.md

@@ -10,8 +10,8 @@
 - [Support Vector Machine Algorithm](support-vector-machine.md)
 - [Artificial Neural Network from the Ground Up](ann.md)
 - [Introduction To Convolutional Neural Networks (CNNs)](intro-to-cnn.md)
-- [TensorFlow.md](tensorflow.md)
-- [PyTorch.md](pytorch.md)
+- [TensorFlow](tensorflow.md)
+- [PyTorch](pytorch.md)
 - [Ensemble Learning](ensemble-learning.md)
 - [Types of optimizers](types-of-optimizers.md)
 - [Logistic Regression](logistic-regression.md)