Merge pull request #551 from geoscixyz/dougoldenburg-patch-2

Landing page: index.rst

Merge pull request #530 from geoscixyz/bug/image-sizes

Image sizes on sounding app

Merge pull request #528 from geoscixyz/ref/intro-apps

Ref/intro apps

Merge pull request #525 from geoscixyz/ref/binder_links

update mybinder links to point to the new version of binders