[releng] updated README.md file
[releng] updated README.md file

Removed unnecessary module list and license count
Added build section with instructions on how to build the entire
repository
b2ihealthcare/snow-owl,IHTSDO/snow-owl,b2ihealthcare/snow-owl,b2ihealthcare/snow-owl,IHTSDO/snow-owl,IHTSDO/snow-owl,b2ihealthcare/snow-owl,IHTSDO/snow-owl