updated README

README.md

 Installation
 ------------
 
-You need Qt4 to build, then:
+You need Qt5 and libX11 (libx11-dev) to build, then:
 
-`qmake-qt4
-make`
+```
+qmake
+make
+```
 
 Additionally, you can copy rd-launcher executable to your path (/usr/local/bin/rd-launcher for example)