Improve finding of python classes

Let's say I want to find out more about `BinaryDilate`
Here are some approaches:
# A)
Looking in the [simpleitk documentation](https://simpleitk.readthedocs.io/en/master/) search get one hit and that is only the migration guide:

# B)
In the C++ API I can only find [BinaryDilateImageFilter](https://simpleitk.org/doxygen/latest/html/classitk_1_1simple_1_1BinaryDilateImageFilter.html)
But that does not help me too much in finding out how to e.g. change the `kernelType` parameter.

# C)
Finally, I can search in the [GithubNotebooks repo](https://github.com/InsightSoftwareConsortium/SimpleITK-Notebooks/search?q=BinaryDilate) but also here, not too much information about setting the parameter.

# Solutions:

# idea i)
adding a notebook into the notebook gallery, where this parameter is set, e.g. something like this:
https://simpleitk.org/doxygen/latest/html/namespaceitk_1_1simple.html#a38998f2c7b469b1ad8e337a0c6c0697b

# idea ii)
adding more documentation about how to set parameters in python at simpleitk.readthedocs.io