Adding README with installation instructions.
Adding README with installation instructions.

zivy/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks,thewtex/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks,thewtex/SimpleITK-Notebooks,thewtex/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks