Update README with general build instructions
Update README with general build instructions

bryanvu/lnd,LightningNetwork/lnd,aakselrod/lnd,BitfuryLightning/lnd,ddustin/lnd,LightningNetwork/lnd,aakselrod/lnd,AndrewSamokhvalov/lnd,AndrewSamokhvalov/lnd,bryanvu/lnd,ddustin/lnd,BitfuryLightning/lnd