Issue #2842141 by hchonov: Document that more specific hooks might be called...

 * rather than implementing hook_form_alter() and checking the form ID, or

 * using long switch statements to alter multiple forms.

 *

 * Form alter hooks are called in the following order: hook_form_alter(),

 * hook_form_BASE_FORM_ID_alter(), hook_form_FORM_ID_alter(). See

 * hook_form_alter() for more details.

 * The call order is as follows: all existing form alter functions are called

 * for module A, then all for module B, etc., followed by all for any base

 * theme(s), and finally for the theme itself. The module order is determined

 * by system weight, then by module name.

 *

 * Within each module, form alter hooks are called in the following order:

 * first, hook_form_alter(); second, hook_form_BASE_FORM_ID_alter(); third,

 * hook_form_FORM_ID_alter(). So, for each module, the more general hooks are

 * called first followed by the more specific.

 *

 * @param $form

 *   Nested array of form elements that comprise the form.

 * one exists) check the $form_state. The base form ID is stored under

 * $form_state->getBuildInfo()['base_form_id'].

 *

 * Form alter hooks are called in the following order: hook_form_alter(),

 * hook_form_BASE_FORM_ID_alter(), hook_form_FORM_ID_alter(). See

 * hook_form_alter() for more details.

 * The call order is as follows: all existing form alter functions are called

 * for module A, then all for module B, etc., followed by all for any base

 * theme(s), and finally for the theme itself. The module order is determined

 * by system weight, then by module name.

 *

 * Within each module, form alter hooks are called in the following order:

 * first, hook_form_alter(); second, hook_form_BASE_FORM_ID_alter(); third,

 * hook_form_FORM_ID_alter(). So, for each module, the more general hooks are

 * called first followed by the more specific.

 *

 * @param $form

 *   Nested array of form elements that comprise the form.