Docs: Improve documentation for `WP_Screen::add_help_tab()`.

Props atachibana.
Fixes #48395.
Built from https://develop.svn.wordpress.org/trunk@46590


git-svn-id: http://core.svn.wordpress.org/trunk@46387 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-screen.php

@@ -594,7 +594,13 @@ final class WP_Screen {
 
 	/**
 	 * Add a help tab to the contextual help for the screen.
-	 * Call this on the load-$pagenow hook for the relevant screen.
+	 *
+	 * Call this on the `load-$pagenow` hook for the relevant screen,
+	 * or fetch the `$current_screen` object, or use get_current_screen()
+	 * and then call the method from the object.
+	 *
+	 * You may need to filter `$current_screen` using an if or switch statement
+	 * to prevent new help tabs from being added to ALL admin screens.
 	 *
 	 * @since 3.3.0
 	 * @since 4.4.0 The `$priority` argument was added.
@@ -603,7 +609,8 @@ final class WP_Screen {
 	 *     Array of arguments used to display the help tab.
 	 *
 	 *     @type string $title    Title for the tab. Default false.
-	 *     @type string $id       Tab ID. Must be HTML-safe. Default false.
+	 *     @type string $id       Tab ID. Must be HTML-safe and should be unique for this menu.
+	 *                            It is NOT allowed to contain any empty spaces. Default false.
 	 *     @type string $content  Optional. Help tab content in plain text or HTML. Default empty string.
 	 *     @type string $callback Optional. A callback to generate the tab content. Default false.
 	 *     @type int    $priority Optional. The priority of the tab, used for ordering. Default 10.

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.4-alpha-46589';
+$wp_version = '5.4-alpha-46590';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.