Oni: Tutorial Proposal: Find across a buffer - `/`, `?`, `n`, `N`

[bryphe]

A helpful tutorial to have would be in searching across a buffer, exercising the following commands:
/ - find
? - find (reverse)
n - next match
N - previous match

A good example for this would be the BasicMovementTutorial: https://github.com/onivim/oni/blob/master/browser/src/Services/Learning/Tutorial/Tutorials/BasicMovementTutorial.tsx

We'd just need to figure out the set of text that makes sense, and add the appropriate Stages.MoveToGoalStage to exercise those motions.

The tutorials are relatively straightforward to add, so this would be a fun and visible first issue if anyone is up for it 👍

[Muream]

I'll give it a shot!

[keforbes]

This was merged in.