Npm-check-updates: Better document .ncurc config options

[JoshuaKGoldberg]

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• [x] I have searched for similiar issues before filing this issue.

Configuration Files

Use a .ncurc.{json,yml,js} file to specify configuration information. You can specify file name and path using --configFileName and --configFilePath command line options.

Could there be a file excerpt or two put in the README.md to demonstrate the suggested usage?

[raineorshine]

How about adding this?

{
  "upgrade": true, 
  "filter": "express"
}

[sanex3339]

Also, it will nice to update example with array variant:

{
  "reject": [
    "@types/estree",
    "ts-node"
  ]
}

[raineorshine]

@sanex3339 Thanks! Done