mention tests in ReadMe and reorg text a little
mention tests in ReadMe and reorg text a little

varunarya10/posix_ipc,varunarya10/posix_ipc,varunarya10/posix_ipc,JioCloud/posix_ipc,varunarya10/posix_ipc,JioCloud/posix_ipc,JioCloud/posix_ipc