If you’ve ever wanted to add explanations or help documentation directly to specific dashboard screen(s), here’s how.
In either a plugin, or your theme’s functions.php file, place this code:
Lines 8-18: Enter your content for this tab. Full HTML allowed. (Watch out for single quotes, as these might break things)
Line 23: Change “Video Documentation” to whatever you want your tab named.
Lines 34 and 37: Choose whether to display on all screens (line 37) or just a specific page (line 34). See here for what the names of different admin screens are named: https://codex.wordpress.org/Administration_Menus#Using_add_submenu_page
Credit to this post for guidance: