Tell users they should set maxsize

README.md

@@ -61,9 +61,9 @@ which gives:
 What follows is the API reference for running the numpy interface.
 Note that most parameters here
 have been tuned with ~1000 trials over several example
-equations, so you don't need to tune them yourself.
+equations, so you likely don't need to tune them yourself.
 However, you should adjust `threads`, `niterations`,
-`binary_operators`, `unary_operators` to your requirements.
+`binary_operators`, `unary_operators`, and `maxsize` to your requirements.
 
 The program will output a pandas DataFrame containing the equations,
 mean square error, and complexity. It will also dump to a csv