ref-manual: Added links to new do_* sections.

With the creation of the new chapter that documents the 51
tasks defined by the OpenEmbedded build system, the remainder
of the ref-manual had many first-instance occurrences of do_*
task names that could be cross-referenced to the new sections.

I have added these links.

(From yocto-docs rev: 2ff39bd226a1d8f11924283bbaa3542a9d936ba3)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/ref-tasks.xml

@@ -189,8 +189,10 @@
         <title><filename>do_populate_sysroot</filename></title>
 
         <para>
-            Copies a subset of files installed by do_install into the sysroot
-            in order to make them available to other recipes.
+            Copies a subset of files installed by the
+            <link linkend='ref-tasks-install'><filename>do_install</filename></link>
+            task into the sysroot in order to make them available to other
+            recipes.
         </para>
     </section>
 
@@ -360,9 +362,11 @@
     <title>Kernel-Related Tasks</title>
 
     <para>
-        The following tasks are applicable to kernel recipes. Some of them
-        (for example do_menuconfig) are also applicable to recipes which use
-        Linux kernel style configuration (e.g. busybox).
+        The following tasks are applicable to kernel recipes.
+        Some of them (e.g. the
+        <link linkend='ref-tasks-menuconfig'><filename>do_menuconfig</filename></link>
+        task) are also applicable to recipes that use
+        Linux kernel style configuration (e.g. BusyBox).
     </para>
 
     <section id='ref-tasks-compile_kernelmodules'>
@@ -377,8 +381,9 @@
         <title><filename>do_diffconfig</filename></title>
 
         <para>
-            Compares the old and new config files after running do_menuconfig
-            for the kernel.
+            Compares the old and new config files after running the
+            <link linkend='ref-tasks-menuconfig'><filename>do_menuconfig</filename></link>
+            task for the kernel.
         </para>
     </section>