[UX] text cleanup for flexible layout templates

[jenlampton]

Layout template settings fieldset:

• Label should change from Layout template settings to simply Settings

• Default region label: Region used for automatic block placement

• Default region description This region is used for the main content when overriding an existing page, and when switching Layout templates that do not have matching region names.

• When blocks are orphaned, The following blocks have been reassigned to the Footer region. The regions they were placed in previously do not exist in the new layout template. You can move them to more appropriate regions: should be simplified/shortened to The following blocks have been reassigned to the Footer region. The regions where these blocks were previously assigned do not exist in the new layout template.

• other?

[stpaultim]

@jenlampton - Should these be combined?

Flexible Layout Templates - better labels for "row width behavior"

[stpaultim]

@jenlampton - is anything here a "Good First Issue"?

I mean text changes usually are, but are any of these clear enough to create a PR?

[jenlampton]

Should these be combined?

Since the other issue is fixed, we can keep this one separate :)

is anything here a "Good First Issue"?

Yes, this would be great! Nice spotting :)