MDL-75759 courseformat: Link classes in PHPDocs with @see tags

- Linking classes/methods mentioned in PHPDoc with @see tags help devs
checking the PHPDoc to quickly navigate to the class/method mentioned
and also helps us ensure that it points to the correct class/method.
- Some typo/grammar fixes as well in existing PHPDoc descriptions.
- Fixed parameter type in execute()'s PHPDoc block.

course/format/classes/external/update_course.php

@@ -72,22 +72,22 @@ public static function execute_parameters(): external_function_parameters {
 
     /**
      * This webservice will execute any action from the course editor. The default actions
-     * are located in core_courseformat\stateactions but the format plugin can extend that class
+     * are located in {@see \core_courseformat\stateactions} but the format plugin can extend that class
      * in format_XXX\course.
      *
-     * The specific action methods will register in a core_courseformat\stateupdates all the affected
-     * sections, cms and course attribute. This object (in JSON) will be send back to the
+     * The specific action methods will register in a {@see \core_courseformat\stateupdates} all the affected
+     * sections, cms and course attribute. This object (in JSON) will be sent back to the
      * frontend editor to refresh the updated state elements.
      *
-     * By default, core_courseformat\stateupdates will register only create, delete and update events
+     * By default, {@see \core_courseformat\stateupdates} will register only create, delete and update events
      * on cms, sections and the general course data. However, if some plugin needs adhoc messages for
-     * its own mutation module, it extend this class in format_XXX\course.
+     * its own mutation module, extend this class in format_XXX\course.
      *
      * @param string $action the action name to execute
      * @param int $courseid the course id
      * @param int[] $ids the affected ids (section or cm depending on the action)
-     * @param int $targetsectionid optional target section id (for move action)
-     * @param int $targetcmid optional target cm id (for move action)
+     * @param int|null $targetsectionid optional target section id (for move action)
+     * @param int|null $targetcmid optional target cm id (for move action)
      * @return string Course state in JSON
      */
     public static function execute(string $action, int $courseid, array $ids = [],

course/format/classes/stateupdates.php

@@ -30,8 +30,8 @@
  *
  * Each format plugin could extend this class to provide new updates to the frontend
  * mutation module.
- * Extended classes should be locate in "format_XXX\course" namespace and
- * extends core_courseformat\stateupdates.
+ * Extended classes should be located in "format_XXX\course" namespace and
+ * extends {@see \core_courseformat\stateupdates}.
  *
  * @package    core_course
  * @copyright  2021 Ferran Recio <ferran@moodle.com>