What would be the effect of deploying a hook with the property 'users.form.add.main =details,organizations'?

Deploying a hook with the property 'users.form.add.main=details,organizations' specifically modifies the layout and content of the user registration form within Liferay. This property indicates that the user form should only include the sections for "details" and "organizations," thereby excluding other default sections, such as "Personal Site."

When this property is applied, it effectively customizes what users see when they are adding new users. The sections mentioned in the property define the specific areas displayed on the form, while any sections not mentioned would be omitted from the form presentation. Therefore, the action of limiting the sections to only those specified results in the exclusion of the Personal Site section, confirming that the effect is that it removes this particular part from the form.

The correct answer emphasizes the customization capabilities Liferay provides when using hooks, showing the flexibility developers have in controlling user experience.