add final linebreak to cargo default help message.
add final linebreak to cargo default help message.

nipunn1313/cargo,rustyhorde/cargo,tshepang/cargo,nipunn1313/cargo,vojtechkral/cargo,eminence/cargo,tshepang/cargo,rustyhorde/cargo,tshepang/cargo,tsurai/cargo,eminence/cargo,tsurai/cargo,vojtechkral/cargo,rustyhorde/cargo,nipunn1313/cargo,vojtechkral/cargo,rust-lang/cargo,rustyhorde/cargo,nipunn1313/cargo,tsurai/cargo,tshepang/cargo,tsurai/cargo,vojtechkral/cargo,rust-lang/cargo,eminence/cargo,rust-lang/cargo,rust-lang/cargo,eminence/cargo,tsurai/cargo