add man page for generate-lockfile subcommand
add man page for generate-lockfile subcommand

eminence/cargo,AndiDog/cargo,brson/cargo,vojtechkral/cargo,tshepang/cargo,AndiDog/cargo,vojtechkral/cargo,tshepang/cargo,tsurai/cargo,rust-lang/cargo,AndiDog/cargo,brson/cargo,nipunn1313/cargo,rustyhorde/cargo,rustyhorde/cargo,durka/cargo,tsurai/cargo,tshepang/cargo,achanda/cargo,eminence/cargo,achanda/cargo,durka/cargo,nipunn1313/cargo,tsurai/cargo,AndiDog/cargo,nipunn1313/cargo,nipunn1313/cargo,tshepang/cargo,vojtechkral/cargo,rust-lang/cargo,achanda/cargo,vojtechkral/cargo,tsurai/cargo,AndiDog/cargo,eminence/cargo,rust-lang/cargo,sbeckeriv/cargo,rust-lang/cargo,sbeckeriv/cargo,achanda/cargo,brson/cargo,durka/cargo,brson/cargo,sbeckeriv/cargo,rustyhorde/cargo,tsurai/cargo,sbeckeriv/cargo,rustyhorde/cargo,durka/cargo,brson/cargo,eminence/cargo