Document in README that ex4.c can be executed.
Document in README that ex4.c can be executed.

fstudio/tinycc,leeduhem/tinycc,andreiw/tinycc,avih/tinycc,acook/tinycc,mobiphil/tinnycc,code4game/tinycc,Archs/TinyCC,code4game/tinycc,yousong/tinycc,fstudio/tinycc,andrewchambers/tccmirror,Archs/TinyCC,mitake/tinycc,Saectar/inherpreter,acook/tinycc,alfonsokim/tinycc,soywiz/tinycc,Saectar/inherpreter,mobiphil/tinnycc,ftdi-paul-jiao/tinyCC,FriedBreakfast/tcc,leeduhem/tinycc,rchandramouli/tinycc,mingodad/tinycc,seyko2/tinycc,fstudio/tinycc,metaeducation/tcc,run4flat/tinycc,code4game/tinycc,soywiz/tinycc,seyko2/tinycc,FriedBreakfast/tcc,andrewchambers/tccmirror,mirror/tinycc,ftdi-paul-jiao/tinyCC,mitake/tinycc,andrewchambers/tccmirror,Wallbraker/DCPU-TCC,seyko2/tinycc,mirror/tinycc,gfwilliams/tinycc,run4flat/tinycc,rchandramouli/tinycc,shinh/nacltcc,Saectar/inherpreter,shinh/nacltcc,gfwilliams/tinycc,mirror/tinycc,run4flat/tinycc,acook/tinycc,metaeducation/tcc,Saectar/inherpreter,run4flat/tinycc,alfonsokim/tinycc,melkior/tinycc,shinh/nacltcc,yousong/tinycc,gfwilliams/tinycc,gfwilliams/tinycc,andreiw/tinycc,rchandramouli/tinycc,acook/tinycc,Saectar/inherpreter,ftdi-paul-jiao/tinyCC,FriedBreakfast/tcc,yousong/tinycc,avih/tinycc,ftdi-paul-jiao/tinyCC,shinh/nacltcc,alfonsokim/tinycc,leeduhem/tinycc,alfonsokim/tinycc,FriedBreakfast/tcc,alfonsokim/tinycc,mingodad/tinycc,fstudio/tinycc,melkior/tinycc,gfwilliams/tinycc,andreiw/tinycc,Wallbraker/DCPU-TCC,andrewchambers/tccmirror,mobiphil/tinnycc,melkior/tinycc,shinh/nacltcc,mitake/tinycc,melkior/tinycc,Wallbraker/DCPU-TCC,metaeducation/tcc,rchandramouli/tinycc,metaeducation/tcc,mitake/tinycc,soywiz/tinycc,seyko2/tinycc,leeduhem/tinycc,avih/tinycc,Archs/TinyCC,soywiz/tinycc,Archs/TinyCC,FriedBreakfast/tcc,mobiphil/tinnycc,mirror/tinycc,leeduhem/tinycc,melkior/tinycc,mingodad/tinycc,run4flat/tinycc,Archs/TinyCC,mingodad/tinycc,fstudio/tinycc,metaeducation/tcc,seyko2/tinycc,rchandramouli/tinycc,andrewchambers/tccmirror,avih/tinycc,yousong/tinycc