[1][gibbsfromncis] Show walkthrough when user opens Exhchange for the first time

[gibbsfromncis]

I've never seen walkthrough before while Dominic didn't say we have this feature.
Also button "help" also should be renamed because it's associate with a ton of documents to read instead of walkthrough

@wmbutler one question. Should I select labels when creating an issue or is this your responsibility?

[gibbsfromncis]

Closed as it was merged