Docs: Add a @since note for the rest_namespace argument of register_post_type() and register_taxonomy().

Use 3-digit, x.x.x-style semantic versioning for `@since` tags of the `$rest_namespace` property in `WP_Post_Type` and `WP_Taxonomy`.

Add a `@since` note to `WP_REST_Taxonomies_Controller::get_item_schema()` for the `visibility` and `rest_namespace` properties.

The `rest_base` property was also added after the method was initially introduced, but that happened during the same release cycle, so it doesn't need a separate `@since` note.

Follow-up to [38832], [39191], [42729], [51959], [51961], [51962], [51964].

See #53399.
Built from https://develop.svn.wordpress.org/trunk@51965


git-svn-id: http://core.svn.wordpress.org/trunk@51554 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api/endpoints/class-wp-rest-taxonomies-controller.php

@@ -301,6 +301,8 @@ class WP_REST_Taxonomies_Controller extends WP_REST_Controller {
 	 * Retrieves the taxonomy's schema, conforming to JSON Schema.
 	 *
 	 * @since 4.7.0
+	 * @since 5.0.0 The `visibility` property was added.
+	 * @since 5.9.0 The `rest_namespace` property was added.
 	 *
 	 * @return array Item schema data.
 	 */