Update README.md with instructions how to build with systemd support (#7730)
Update README.md with instructions how to build with systemd support (#7730)

#7728 - update instructions for systemd support
ctripcorp/redis,PKRoma/redis,oranagra/redis,PKRoma/redis,PKRoma/redis,antirez/redis,yossigo/redis,neomantra/redis,neomantra/redis,ofirluzon/redis,charsyam/redis,PKRoma/redis,PKRoma/redis,ctripcorp/redis,soloestoy/redis,antirez/redis,yossigo/redis,oranagra/redis,oranagra/redis,neomantra/redis,charsyam/redis,antirez/redis,charsyam/redis,ctripcorp/redis,antirez/redis,ofirluzon/redis,neomantra/redis,ctripcorp/redis,oranagra/redis,ofirluzon/redis,oranagra/redis,soloestoy/redis,soloestoy/redis,ofirluzon/redis,neomantra/redis,soloestoy/redis,ofirluzon/redis,yossigo/redis,yossigo/redis,charsyam/redis,charsyam/redis,yossigo/redis,soloestoy/redis