std.logger has an ostensibly broken example and wrong docs

[0xEAB]

std.logger provides a poor out-of-the-box experience.

• Its hello-world example seems to be a no-op to the unsuspecting user as it prints nothing in the default configuration.

• Furthermore, certain information in the docs is plain wrong as it never got updated throughout the revisions the code received.

  The default Logger will by default log to stderr and has a default LogLevel of LogLevel.all.

  This is wrong.

These issues sum up and lead to confusion (#10573) and scorn.