v0.1.0-rc5 Add TaskStatus and Motivation types

✨ Features
- tasks: Add new types for TaskStatus and Motivation. Replaced raw
  strings with typed constants

📚 Documentation
- Fix PersonBuilder example to use RelationshipCloseFriend constant
- Add godoc links for RelationshipCloseFriend, ErrUnauthorized
-----BEGIN SSH SIGNATURE-----
U1NIU0lHAAAAAQAAAEoAAAAac2stc3NoLWVkMjU1MTlAb3BlbnNzaC5jb20AAAAgzEkAhr
f0dc6ZiSJXHc/mDhl7rRRGcNCSuENi7R/pfKkAAAAEc3NoOgAAAANnaXQAAAAAAAAABnNo
YTUxMgAAAGcAAAAac2stc3NoLWVkMjU1MTlAb3BlbnNzaC5jb20AAABAm+L3quq1AEQf71
UqkNXaQEwFSZEeGxGeERxR5/0sH1KAbDSQy5j+aU3lyQWThk7hZqwy866HEzSscC8xsOr2
BwEAAKy3
-----END SSH SIGNATURE-----