fix(#13,doc): code to plot workflow diagram in intro

Author: ankostis

docs/source/index.rst

@@ -67,6 +67,10 @@ Here's a Python script with an example GraphKit computation graph that produces
    # Prints "{'a_minus_ab': -8}".
    print(out)
 
+   # Plot workflow diagram in a matplotlib window (`graphviz` in the path needed)
+   graph.net.plot(show=True)
+
+
 As you can see, any function can be used as an operation in GraphKit, even ones imported from system modules!
 
 License