877792: modified heading of executeCommand and included insertAudio & insertVideo in RichTextEditor(Mvc/Core)#3994

saravanangn merged 1 commit intohotfix/hotfix-v28.2.3syncfusion-content/ej2-asp-core-mvc-docs:hotfix/hotfix-v28.2.3from

877792-ExecMvcCoresyncfusion-content/ej2-asp-core-mvc-docs:877792-ExecMvcCoreCopy head branch name to clipboard