Update creating-a-new-model.md

Defined property `newTitle` on `TodosController` with default value of empty string. Without this, line `if (!title.trim()) { return; }` will throw _Uncaught TypeError: Cannot call method 'trim' of undefined_ when trying to submit an empty string.
Update the-rest-adapter.md

Plurals dealing with an API need to be underscored.
Add cookbook section
Add some additional information about the filterProperty and invoke methods.
update checkbox binding logic error

if isAdministrator is false, then checkbox is disabled, not the other way.
added guides/understanding-ember/debugging page
Update debugging.md
Update debugging.md
Merge pull request #588 from cavneb/master

Added debugging page in the guide
correcting fixture adapter example
Merge pull request #589 from twokul/master

correcting fixture adapter example
use activate hook rather than the private enter
Merge pull request #590 from jasonkriss/patch-1

use activate hook rather than the private enter
Adding Verisk Health to  user logos
Merge pull request #592 from kingpin2k/master

Adding Verisk Health to  user logos
Update debugging.md: added LOG_VIEW_LOOKUPS and LOG_ACTIVE_GENERATION
Merge pull request #594 from heyjinkim/master

Update debugging.md: added LOG_VIEW_LOOKUPS and LOG_ACTIVE_GENERATION
Update testing guide: add test adapters note, clarify the ending note
Merge pull request #595 from pixelhandler/testing-guide

Update testing guide: add test adapters note, clarify the ending note
bump to ember 6.1