8043975: Update README for jdk9

Reviewed-by: tbell

README

@@ -1,15 +1,15 @@
 README:
   This file should be located at the top of the OpenJDK Mercurial root
   repository. A full OpenJDK repository set (forest) should also include
-  the following 6 nested repositories:
-    "jdk", "hotspot", "langtools", "corba", "jaxws"  and "jaxp".
+  the following 7 nested repositories:
+    "jdk", "hotspot", "langtools", "nashorn", "corba", "jaxws"  and "jaxp".
 
   The root repository can be obtained with something like:
-    hg clone http://hg.openjdk.java.net/jdk8/jdk8 openjdk8
+    hg clone http://hg.openjdk.java.net/jdk9/jdk9 openjdk9
   
   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
+    cd openjdk9 && sh ./get_source.sh
 
   People unfamiliar with Mercurial should read the first few chapters of
   the Mercurial book: http://hgbook.red-bean.com/read/
@@ -19,9 +19,9 @@ README:
 Simple Build Instructions:
   
   0. Get the necessary system software/packages installed on your system, see
-     http://hg.openjdk.java.net/jdk8/jdk8/raw-file/tip/README-builds.html
+     http://hg.openjdk.java.net/jdk9/jdk9/raw-file/tip/README-builds.html
 
-  1. If you don't have a jdk7u7 or newer jdk, download and install it from
+  1. If you don't have a jdk8 or newer jdk, download and install it from
      http://java.sun.com/javase/downloads/index.jsp
      Add the /bin directory of this installation to your PATH environment
      variable.
@@ -37,4 +37,4 @@ where make is GNU make 3.81 or newer, /usr/bin/make on Linux usually
 is 3.81 or newer. Note that on Solaris, GNU make is called "gmake".
 
 Complete details are available in the file:
-     http://hg.openjdk.java.net/jdk8/jdk8/raw-file/tip/README-builds.html
+     http://hg.openjdk.java.net/jdk9/jdk9/raw-file/tip/README-builds.html