Link docs to example folder

[odunbar]

Issue

Arising in our CES-sister repo. Commonly users read the docs and do not realize that there are fully coded examples the docs refer to. In particular the docs snippets may not reproducible, but the examples are.

Solution

Add an info block with a link to the examples directory may help folks run the example code.

e.g. the solution here
CliMA/CalibrateEmulateSample.jl#290