DOC: Remove placeholder for tutorial 3

Also fix typo in rummary.rst

Author: Jacob-Stevens-Haas

docs/summary.rst

@@ -115,7 +115,7 @@ Structure of PySINDy
 The submodules of PySINDy are each aligned with one of the terms in
 the aforementioned approximation equation, :math:`\dot X \approx \Theta(X)\Xi.`
 
- * ``pysindy.differentiate`` performs numerical differentiation to compute :math:`\dot X` from :math:`X`;
+ * ``pysindy.differentiation`` performs numerical differentiation to compute :math:`\dot X` from :math:`X`;
  * ``pysindy.feature_library`` allows the user to specify a set of library functions and handles the formation of :math:`\Theta(X)`;
  * ``pysindy.optimizers`` provides a set of sparse regression solvers for determining :math:`\Xi`.
 

examples/README.rst

@@ -18,22 +18,15 @@ We show how to use PySINDy to learn a model for a simple linear differential equ
 `Evaluating a model fit <./tutorial_2/example.ipynb>`_
 ---------------------------------------------------------------------------------------------------------------------
 
-.. toctree::
-    :hidden:
-    :maxdepth: 1
-
-    ./tutorial_2/example
-
-
-`Choosing model components <./tutorial_3/example.ipynb>`_
----------------------------------------------------------------------------------------------------------------------
-
+It can be tricky to evaluate how well a model is fit.
+This tutorial shows different ways to evaluate and visualize a model,
+depending on the use case.
 
 .. toctree::
     :hidden:
     :maxdepth: 1
 
-    ./tutorial_3/example
+    ./tutorial_2/example
 
 
 `Feature overview <./1_feature_overview/example.ipynb>`_