ref-manual: Added "debug-with-srcpkg" option to package split variable

Added the "debug-with-srcpkg" option for the PACKAGE_DEBUG_SPLIT_STYLE
variable.

(From yocto-docs rev: 05c51e53059bf7c999a448402d60d0b16d62341b)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/ref-variables.xml

@@ -9646,6 +9646,12 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
                             ".debug" previously described with the exception
                             that no source files are installed.
                             </para></listitem>.
+                        <listitem><para>
+                            "debug-with-srcpkg": The same behavior as
+                            ".debug" previously described with the exception
+                            that all source files are placed in a separate
+                            <filename>*-src</filename> pkg.
+                            </para></listitem>
                     </itemizedlist>
                 </para>