Improve plugins documentation (step 4, product name should be the same)

[Janez Svetin]

see: https://bizzthemes.com/forums/topic/google-calendar-2/page/3/#post-121648

Zeljan, this is very important: The documentation has to be updated. It says there in step 4 that you can choose “any” name for the Product Name. In fact, and Jana is right, you have to choose exactly the same name as the project name (please see screenshot and Jana’s explanation above).

[Željan Topić]

Fixed https://bizzthemes.com/help/setup/wc-appointments/google-calendar-integration/