Update docs to show the list of supported config files.

[jayvdb]

https://github.com/streetsidesoftware/vscode-spell-checker/blob/main/design-docs/wip/configuration.md supports

These include cspell.json, cspell.config.yaml, and cspell.config.js. When spell checking files, the spell checker searches the directory hierarchy looking for configuration files. ...

The docs for this CLI says it only supports cspell.json as default.

[Jason3S]

@jayvdb,

The cli supports a wide range a configuration locations. See: configLocations.ts#L11-L52

The challenge is to keep the documentation up to date.