Spell it out which sub-menus are affected by Maximum number to display setting

Problem/Motivation

It is not immediately clear which sub-menus are affected by the "Maximum number of bundle sub-menus to display" setting under Admin Toolbar Tools, see #3261664: Bundle sub-menu maximum not honored.

Many users probably don't even know what a bundle is ... they may just notice that under some menus, the number of items are limited to the maximum number, whereas under other, all are shown -- for example Views or Roles.

Steps to reproduce

Set "Maximum number of bundle sub-menus to display" to 2, and see that only some sub-menus are affected, but others are not, but not understand why.

Proposed resolution

Make it clear which sub-menus are affected by updating the text in the form.

Now

Better?

Remaining tasks

User interface changes

API changes

Data model changes