Jupyter examples

[manthey]

We should highlight that Jupyter notebook examples that are stand-alone. For instance, the color deconvolution notebook can be run in google colab by just adding a pip install command as first block (e.g., !pip install histomicstk --find-links https://girder.github.io/large_image_wheels). Others require connection to a non-anonymous girder server, so wouldn't be called out.

This should probably be adding a readme that lists these examples in particular. For each example, we may want to add a block like

Open in [google colab](https://colab.research.google.com/github/DigitalSlideArchive/HistomicsTK/blob/master/docs/examples/color_deconvolution.ipynb).

at the top of the example.

Further, if we want to access a girder server as part of an example with anonymous access, we can use demo.kitware.com/histomicstk. We should copy items used in examples to an appropriately named collection there.