Modifying the default ‘Thank you for creating with WordPress‘ footer credits in the admin area is a somewhat popular way for asking for a rating or adding a link to the support forums in a very available but not in-the-way place.
To name a few plugins from the top of my head that change these credits: WooCommerce, Ninja Forms, Easy Digital Downloads etc.
It is important to keep in mind that if you decide you want to modify the credits, is that you should only do this on the plugin specific pages and not throughout the entire WordPress admin.
Here’s what WooCommerce currently does on the WooCommerce related pages:
Easy Digital Downloads asks for a review, which seems to be a highly effective and non-intrusive way of doing so:
Changing the credits
Now the actual code snippet on how you can actually change it yourself.
Lines #8 and #10 should be uncommented and modified accordingly so these credits only show on your plugin’s pages.