Add favicon to the Flow Production Tracking API documentation

[sungbinlee]

Description

I've noticed that the Flow Production Tracking API documentation lacks of a favicon, leading to difficulty in distinguishing the tab from others. I'm a frequent user of the documentation, and when multiple tabs are open, it becomes challenging to relocate the correct tab due to the absence of a favicon. To improve usability, I propose adding a favicon to the documentation. This would greatly enhance the user experience by allowing users to quickly identify the documentation tab.

Screenshot