[Tutorial] Add a section in the Context Management on Elron's context manager session feature.

[nrfulton]

LGTM. We need to create some documentation about this, probably in the Context Management section of the tutorial I'll create a new issue for this and merge for now, so that we're not gating a new feature on docs.

Originally posted by @nrfulton in #55 (comment)

[psschwei]

removed