Simply put, in project management, Gold Plating "refers to the addition of any feature not considered in the original scope plan". PMI actually red flags gold plating as being a bad practice (PMBOK Guide). I agree. In a "project context" it's a bad practice to do something that's out of scope and not included in the project plan. That simple.
However, in an "operations context", I'm a fan of the "Deliver more than expected" mindset (Larry Page). If, on your day-to-day normal operation, you have a small time window to go beyond what's required, DO IT!
Suppose your work is to monitor a farm of specific apps or whatever. You saw an opportunity to improve your daily work and, as expected, you develop a tool to ease your life. Cool, just normal work. BUT, if you can go further on and build a small documentation and make it available to all the company, BETTER. If it's so good and you can pitch it to another client with similar environment, amazing. If another client (and another, and another...) ends up buying it, PERFECT!
– In Projects: "Deliver as expected".
– In Operations: "Deliver more than expected".