New generator request: Faker::Commerce.rating

[bradly]

Is your feature request related to a problem? Please describe it.
I had a need for product ratings/number of stars. A rating by by default is float with one decimal between 0 and 5. I.e. 3.6

For example, if proposing a new generator, explain why it's useful and relevant to Faker, and examples of how to use it in a real project.

Describe alternatives you've considered
I considered using Faker::Number.decimal, but I can't limit the range to 0-5, only the number of digits on each side of the decimal.

I've also considered creating this outside of Commerce so it can be used for a Book, App, Restaurant, etc., but decided to kept it as simple as possible.

Additional context
Since the return value is numeric, no translations are needed.

Updated docs

[bradly]

I didn't see the checkbox to open an issue before writing any code, so I did things a bit out of order here and already opened a pr in #2808. Sorry about that.

[stefannibrasil]

No worries, thanks for the screenshot, that's neat! I left some comments in the PR.

I don't have lots of background with product ratings but you mention here that the default is a decimal. I've mostly seen integers, though. Mainly because I use the 5 start reviews when I rate something :P Would it be helpful to allow decimals but have an integer as the default?