updated config.toml to be up to date with README.md

[PascalKont]

I noticed the config.toml file has old content that throws an error when used.

Error reading config file: Decoding toml failed: TOML parse error at line 48, column 1
|
48 | first = "#00ffff"
| ^^^^^
unknown field first, expected palette or custom

So i updated the config to be in sync with the README.md

[RobertMueller2]

Thanks for catching that one. Hopefully with #200 we can automate this at some point ;)