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:
A very elegant message, same-like to the official WordPress one.
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.
Jeroen Sormani
I'm a professional WordPress plugin developer on a mission to create the best plugins for my clients. I'm specialised in developing general WordPress, WooCommerce and Easy Digital Downloads plugins.
Interested in talking about a WordPress project? Get in touch!
Who’s this guy?
My name is Jeroen, go ahead and try to pronounce that! I bet you get it wrong if you’re not Dutch 
I am a professional WordPress Plugin Developer, working from Alphen aan den Rijn in the Netherlands. Besides being a seasoned developer, I have a solid background in SEO and have been responsible for hundreds of websites and webshops in my previous work experience.
I build custom plugins for WordPress, WooCommerce and Easy Digital Downloads. My focus is to build the best, secure, reliable, optimized plugins with a good User Experience.
When not working, I like to watch tv series and eat some healthy home-made pizza.