Fixed example of Rich Presence config file to be valid VDF

[mynameiswhm]

The current example in the docs isn't a valid localization file and was rejected by Steamworks with not very informative error message: "Unknown/unsupported language 'language' in file."

I've changed the example to be a valid localization VDF format. I've also added the suggestion to save the file as .vdf since the upload form expects this extension — I've managed to upload any file from macOS just by dragging it into the upload dialog, but I'm not sure if that's the case for another operating systems.

Another (probably better) alternative would be to just re-use the entire code snippet from official Steamworks documentation, as it more clearly shows token referencing from other tokens (but I'm not sure whether that's an NDA violation :D)

[Gramps]

Hey there! Ah, I guess if it is a .vdf file, they require different data. This is the file I used for Skillet, it works perfectly fine when uploaded to Steamworks and renders everything. I guess they accept more than one format but are sticklers for the .vdf one.

I did notice something similar with the Inventory item files. If you give it a .vdf extension, it must be formatted a specific way but if it is .json it can be very different.

I don't think that'd be a violation of NDA since it is on a public documentation site.