GUACAMOLE-708: Update documentation regarding changes in TOTP prereqs.
GUACAMOLE-708: Update documentation regarding changes in TOTP prereqs.

TOTP no longer requires self update permission for users, instead
leveraging getPrivileged() to obtain temporary privileged access for
storing user attributes.

mike-jumper/incubator-guacamole-manual,mike-jumper/incubator-guacamole-manual,mike-jumper/incubator-guacamole-manual