doc: update gyp build instructions

README.md

@@ -56,7 +56,7 @@ http://nodejs.org/
 For GCC (including MinGW) there are two methods building: via normal
 makefiles or via GYP. GYP is a meta-build system which can generate MSVS,
 Makefile, and XCode backends. It is best used for integration into other
-projects.  The old (more stable) system is using Makefiles.
+projects.  The old system is using plain GNU Makefiles.
 
 To build via Makefile simply execute:
 
@@ -69,15 +69,22 @@ related files.
 Windows users can also build from cmd-line using msbuild.  This is
 done by running vcbuild.bat from Visual Studio command prompt.
 
-To have GYP generate build script for another system you will need to
-checkout GYP into the project tree manually:
+To have GYP generate build script for another system, make sure that
+you have Python 2.6 or 2.7 installed, then checkout GYP into the
+project tree manually:
 
+    mkdir -p build
     svn co http://gyp.googlecode.com/svn/trunk build/gyp
 
+Or:
+
+    mkdir -p build
+    git clone https://git.chromium.org/external/gyp.git build/gyp
+
 Unix users run
 
     ./gyp_uv -f make
-    make
+    make -C out
 
 Macintosh users run