docs: Explanations for the View

[neznaika0]

Description
Improving the description View.

• We don't have a test to check using Cell getDataProperty(), getViewProperty() or $this->data, $this->view. I didn't quite understand the prohibition for data.
• The $view property is not specified, as this is the fullpath to the file, and not, as for the View, a relative name (with a namespace Blog\Cells\alerts).
• I came across a misunderstanding of how include() works, so I described my case.
• The Views folder in namespace is optional - the locator always searches for this folder.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide