Add `ico` to list of supported types in the readme
Add `ico` to list of supported types in the readme

Ref https://github.com/sindresorhus/file-type/commit/0953b333d15c51421a88908dc301ec637ce869f3

trexnix/file-type,sindresorhus/file-type,sindresorhus/file-type,magicode/file-type,ImageMetrics/file-type