ResourceLoader.load_threaded_get_status progress percentage not well documented

### Tested versions

- In 4.3.dev (b15105a3585c29c8448f3d2dc8fe20a578a2b41b)

### System information

N/A

### Issue description

Quoting this doc: https://docs.godotengine.org/en/stable/classes/class_resourceloader.html#class-resourceloader-method-load-threaded-get-status

> An array variable can optionally be passed via progress, and will return a one-element array containing the percentage of completion of the threaded loading.

This does not document the type of the array and the value range that the programmer should expect, so they have to figure it out with guesswork and experimentation.

Perhaps it could be changed to:

> An array variable can optionally be passed via progress, and will return a one-element float array in the range 0.0 to 1.0 representing the percentage of completion of the threaded loading.

### Steps to reproduce

N/A

### Minimal reproduction project (MRP)

N/A

Start with the ResourceLoader class documentation at the linked load_threaded_get_status method. Update the progress parameter description to state its array type and the 0.0 to 1.0 value range, then verify that the rendered documentation accurately reflects the clarification.

Written by the indexing model from the issue text.