Update README.md

Link to cogent3 docs in README

README.md

@@ -7,7 +7,7 @@
 
 <!-- [![Coverage Status](https://coveralls.io/repos/github/iqtree/piqtree2/badge.svg?branch=main)](https://coveralls.io/github/iqtree/piqtree2?branch=main) -->
 
-piqtree2 is a library which allows you use IQ-TREE directly from Python!
+`piqtree2` is a library which allows you use IQ-TREE directly from Python! The interface with python is through [cogent3](https://cogent3.org) objects, as shown below.
 
 ## Note
 
@@ -31,8 +31,12 @@ tree = build_tree(aln, "JC", rand_seed=1) # Optionally specify a random seed.
 
 print("Tree topology:", tree) # A cogent3 tree object
 print("Log-likelihood:", tree.params["lnL"])
+# In a Jupyter notebook, try tree.get_figure() to see a dendrogram
 ```
 
+> **Note**
+> See the [cogent3 docs](https://cogent3.org) for examples on what you can do with cogent3 trees.
+
 ### Fit Branch Lengths to Tree Topology
 
 ```python
@@ -85,4 +89,4 @@ tree3 = make_tree("(a,b,(d,(c,e)));")
 pairwise_distances = robinson_foulds(tree1, tree2, tree3) # Supports any number of trees (for a sequence of trees use *seq_of_trees)
 
 print(pairwise_distances) # A numpy array containing pairwaise Robinson-Foulds distances between trees
-```
+```