Wp-calypso: Gutenboarding: Add a notice giving the user some context when they land in the editor

[johnHackworth]

When the user lands in the editor for the first time, the experience may be a little bit disorienting. We need to add a Gutenberg notice with this text (or a variation, ping @rickybanister )

"this is the content of your front page. To see how the entire site will look like you can click on 'preview'"

[joanrho]

@johnHackworth were you thinking something like this as a one time notice?

[simison]

Component for the above design: https://github.com/WordPress/gutenberg/blob/b12aab0364ed2d91e3cf914b3a7590de030574bd/packages/components/src/notice/README.md

[simison]

@joanrho just FYI, it can also contain an icon if needed. :-)

[ramonjd]

The copy that refers to the "top bar" might be confusing.

We're not showing a preview a button at all before launch (we're hiding it)

Should we think about putting it back?

[simison]

@ramonjd hiding the preview button was accidental, adding it back here: https://github.com/Automattic/wp-calypso/pull/41470

[ramonjd]

Some relevant slack convo: p1588009089077100-slack-CPFFQTG69

[yansern]

PR for this here: https://github.com/Automattic/wp-calypso/pull/41661

[simison]

There's a welcome modal now in editor so I'll close this.