fix: Remove -v shortcut for --verbose, conflicts with --version

[tbarlow12]

What did you implement:

Currently, if you were to run sls --version or sls -v, the plugin causes it to fail because the LoggingService creates a shortcut for --verbose, which is -v. This conflicts with --version. This PR removes that shortcut and updates the documentation.

How did you implement it:

Only look for the full verbose flag within the options, set log level to info if undefined.

How can we verify it:

Run sls --version. It shouldn't fail.

Todos:

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Is this ready for review?: YES
Is it a breaking change?: NO

[pjlittle]

LGTM - thanks for fixing, we definitely shouldn't be stomping/failing on this.