Print errors by default (log-level = info)

[skunert]

When checking prdoc files, I am interested in the actual errors. They are already printed,
but default log level is none. IMO it should be info.

Example output after change:

[2024-02-26T08:42:53Z INFO  prdoclib::commands::check] Checking directory prdoc
[2024-02-26T08:42:53Z INFO  prdoclib::commands::check] Using schema: /Users/sebastian/work/repos/polkadot-sdk/prdoc/schema_user.json
[2024-02-26T08:42:53Z INFO  prdoclib::commands::check] errors: [
        Properties {
            path: "",
            detail: "Additional property 'tle' is not allowed",
        },
        Required {
            path: "/title",
        },
    ]
[2024-02-26T08:42:53Z INFO  prdoclib::commands::check] missing: []
[2024-02-26T08:42:53Z ERROR prdoclib::commands::check] NumberNotFound(3002)
PR #3243 -> ERR
PR #3002 -> ERR
Checked 2 files.