Rework dummy post-content to be a "welcome" tutorial

[mtias]

Let's use the default post to describe how the editor works, what you can do, the main interaction patterns, default blocks, etc.

[BE-Webdesign]

I was also thinking we could build in some user guides into the plugin; a help section of sorts.

[jasmussen]

I was also thinking we could build in some user guides into the plugin; a help section of sorts.

Just opened a ticket for porting the help button in #599. In addition to this, there's a ticket for using WordPress pointers in #592. Perhaps these two tickets combined can accomplish this?

[jasmussen]

Closing as fixed, as this is in master!