readme: use --destdir option to install engine in selected folder

README.md

@@ -81,16 +81,16 @@ Even if Xash3D FWGS does support targetting 64-bit, you can't load games without
 0) Open command line
 1) Navigate to `xash3d-fwgs` directory.
 2) Carefully examine which build options are available: `waf --help`
-3) Configure build: `waf configure -T release --sdl2=c:/path/to/SDL2 --prefix=c:/path/to/any/output/directory`
+3) Configure build: `waf configure -T release --sdl2=c:/path/to/SDL2`
 4) Compile: `waf build`
-5) Install: `waf install`
+5) Install: `waf install --destdir=c:/path/to/any/output/directory`
 
 #### Linux
 0) Examine which build options are available: `./waf --help`
-1) Configure build: `./waf configure -T release --prefix=/path/to/any/output/directory`
+1) Configure build: `./waf configure -T release`
 (You need to pass `-8` to compile 64-bit engine on 64-bit x86 processor)
 2) Compile: `./waf build`
-3) Install(optional): `./waf install`
+3) Install(optional): `./waf install --destdir=/path/to/any/output/directory`
 
 Note: if compiling 32-bit on amd64, you may need to supply `export PKG_CONFIG_PATH=/usr/lib/i386-linux-gnu/pkgconfig` prior to running configure.