End-user documentation for waifu2x "type" choices

[hjk321]

Currently, the GUI has several choices for the model used but there is no documentation on the similarities and differences of each "type". As it stands, new users will either have to blindly guess or just go with the default. I propose a help button be added that would give details on each choice, including:

• Brief description of choice
• Relative processing time
• Relative output quality
• Limitations/Caveats
• Example use case (i.e. why choose this one over the others)

The default vulkan option seems to be what most people need, but it would be better if the end user could make a more informed choice.