8004712: build-infra: Move user guide from web pages to repository

Summary: Just the initial work, will need more changes.
Reviewed-by: tbell

README

 README:
   This file should be located at the top of the OpenJDK Mercurial root
-  repository. This root repository will include a "make" directory,
-  and a Makefile for building the entire OpenJDK.
-  A full OpenJDK repository set (forest) should also include the following
-  6 nested repositories:
+  repository. A full OpenJDK repository set (forest) should also include
+  the following 6 nested repositories:
     "jdk", "hotspot", "langtools", "corba", "jaxws"  and "jaxp".
-  There are also several source downloads for the jax* repositories that
-  will be needed.
-
-  This one root repository can be obtained with something like:
 
+  The root repository can be obtained with something like:
     hg clone http://hg.openjdk.java.net/jdk8/jdk8 openjdk8
   
-  To make sure you have all the nested repositories, you can run the
-  get_source.sh script located in the same respository as this file:
-
+  You can run the get_source.sh script located in the root repository to get
+  the other needed repositories:
     cd openjdk8 && sh ./get_source.sh
 
   People unfamiliar with Mercurial should read the first few chapters of
   the Mercurial book: http://hgbook.red-bean.com/read/
 
-  See http://openjdk.java.net/ for more information about the OpenJDK.
+  See http://openjdk.java.net/ for more information about OpenJDK.
 
 Simple Build Instructions:
   
   0. Get the necessary system software/packages installed on your system, see
-     http://hg.openjdk.java.net/jdk8/build/raw-file/tip/README-builds.html
+     http://hg.openjdk.java.net/jdk8/jdk8/raw-file/tip/README-builds.html
 
-  1. If you don't have a jdk6 installed, download and install a JDK 6 from
+  1. If you don't have a jdk7u7 or newer jdk, download and install it from
      http://java.sun.com/javase/downloads/index.jsp
-     Set the environment variable ALT_BOOTDIR to the location of JDK 6.
+     Add the /bin directory of this installation to your PATH environment
+     variable.
 
-  2. Check the sanity of doing a build with your current system:
-       make sanity
-     See README-builds.html if you run into problems.
+  2. Configure the build:
+       bash ./configure
   
-  3. Do a complete build of the OpenJDK:
+  3. Build the OpenJDK:
        make all
-     The resulting JDK image should be found in build/*/j2sdk-image
+     The resulting JDK image should be found in build/*/images/j2sdk-image
 
 where make is GNU make 3.81 or newer, /usr/bin/make on Linux usually
-is 3.81 or newer.
+is 3.81 or newer. Note that on Solaris, GNU make is called "gmake".
 
-Complete details are available in README-builds.html.
+Complete details are available in the file:
+     http://hg.openjdk.java.net/jdk8/jdk8/raw-file/tip/README-builds.html