[Example] Add TorchMetrics in README (#3913)

* Update README.md

* Update README.md

* Update README.md
Co-authored-by: Rhett Ying <85214957+Rhett-Ying@users.noreply.github.com>

examples/pytorch/cluster_gcn/README.md

@@ -10,7 +10,7 @@ Dependencies
 - Python 3.7+(for string formatting features)
 - PyTorch 1.9.0+
 - sklearn
-
+- TorchMetrics
 
 ## Run Experiments
 

examples/pytorch/graphsage/README.md

@@ -9,13 +9,11 @@ Advanced usages, including how to run pure GPU sampling, how to train with PyTor
 
 Requirements
 ------------
-- requests
 
 ```bash
-pip install requests
+pip install requests torchmetrics
 ```
 
-
 Results
 -------
 

examples/pytorch/rgat/README.md

 Relational GAT
 ==============
 
+Requirements:
+- TorchMetrics
+
 This is an adaptation of RGCN where the graph convolution is replaced with graph attention.
 
 Run