fixes #625 - adds link to API license to legal README.md
fixes #625 - adds link to API license to legal README.md

NinjaMSP/crossbar,NinjaMSP/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,NinjaMSP/crossbar,w1z2g3/crossbar,w1z2g3/crossbar