Add docbook style sheets to README to speed up build time

The w3C has implemented measures to discourage excessive DTD traffic
and to encourage caching the XML.  See,

The W3C servers are slow to return DTDs. Is the delay intentional?
http://www.w3.org/Help/Webmaster.html#slowdtd

Caching XML data at install time
http://www.w3.org/QA/2008/09/caching_xml_data_at_install_ti.html

Many GNU/Linux distributions conveniently include these docbook
style sheets in a package.  This package has been added to the
dependencies for building from source.

Also added and updated are commands related to installation on
OpenSUSE.

README

@@ -45,6 +45,10 @@ a. Pre-built Binary
       su -
       yum install gparted
 
+      OpenSUSE
+      --------
+      sudo zypper install gparted
+
 b. Building from Source
 
    Building Gparted from source requires that several dependencies are
@@ -60,19 +64,20 @@ b. Building from Source
    following command;
       sudo apt-get install build-essential e2fsprogs uuid uuid-dev \
                            gnome-common libparted-dev libgtkmm-2.4-dev \
-                           libdevmapper-dev gnome-doc-utils
+                           libdevmapper-dev gnome-doc-utils docbook-xml
 
    On Fedora, you will need to run (as root);
       yum install gtkmm24-devel parted-devel e2fsprogs-devel gettext \
                   'perl(XML::Parser)' desktop-file-utils libuuid-devel \
-                  gnome-doc-utils rarian-compat
+                  gnome-doc-utils docbook-dtds rarian-compat
       yum groupinstall 'Development Tools'
 
    On openSUSE, these dependencies may be obtained by running the
-   following command;
-      sudo zypper install automake autoconf gcc-g++ make gnome-common \
+   following commands;
+      sudo zypper install automake autoconf make gnome-common \
                           libuuid-devel parted-devel gtkmm2-devel \
-                          gnome-doc-utils-devel
+                          gnome-doc-utils-devel docbook-xsl-stylesheets
+      sudo zypper install -t pattern devel_c_c++
 
    Briefly, the shell commands `./configure; make; make install' should
    configure, build, and install this package.