use magic command to get samples and snippet to help notebook users get unblocked / discover

[colombod]

using something like #!how-do-I import a package the user could be presented with content and a cell with code ready to go that will show how to do that.

The command should be kernel aware and make the right suggestion when invoked in powershel kernel instead of csharp

[jonsequitur]

Suggestions for command names (and these might point to variations on the scenario):

• #!help
• #!hint