Update "Unified Toolbar" name mode to "Top Toolbar" for clarity.

[mtias]

Small copy change to improve clarity of this mode:

[youknowriad]

LGTM . 👍

[afercia]

Just noting "Unified Toolbar" was clearer to me. Not sure where this change has been discussed and what the argumentation is.

[0aveRyan]

This change should have been discussed, it affects docs work already done and added confusion to this morning's #core-editor meeting 😕Also, Top Toolbar adds some potential confusion with the wp admin bar for users reading docs.

[earnjam]

@mtias Can you clarify whether there was any discussion about making this change? I never saw any examples of reports of confusion about the term "Unified Toolbar", so this comes as a surprise to me. I wasn't aware it was changed until it came up in the #core-editor chat yesterday. I asked about it there shortly after, but no one responded.

FWIW, I actually think this is a step backward in clarity. To me, "Top Toolbar" is more confusing than "Unified Toolbar". There is always a top toolbar present whether this mode is on or not. When active, this mode “unifies” the two types of toolbars (editor toolbar and block toolbar) into one. Even the description reads like an explanation of the word “unified”. Access all block and document tools in a single place (That description is also inaccurate because not all block and document tools are there...many are in the sidebar. But that's for a different discussion)

I realize this is bikeshedding, but the bigger concern I have is more in why we would change the name of a major piece of functionality the day before the RC is released without any discussions or even an issue dedicated to it.