ref-manual: Fleshed out the do_compile task.

Fixes [YOCTO #9964]

Added more detailed information to the do_compile task.  Also, provided
some information about oe_runmake in the base.bbclass refrence.
Finally, put some detail in the "Shared State" section concerning
do_deploy[dirs].

(From yocto-docs rev: 5d0612a57cc8e035a2194ada21e65055ef2b8a2e)

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

documentation/ref-manual/ref-tasks.xml

@@ -69,9 +69,19 @@
         <title><filename>do_compile</filename></title>
 
         <para>
-            Compiles the source in the compilation directory, which is pointed
-            to by the
-            <link linkend='var-B'><filename>B</filename></link> variable.
+            Compiles the source code.
+            This task runs with the current working directory set
+            to
+            <filename>${</filename><link linkend='var-B'><filename>B</filename></link><filename>}</filename>.
+        </para>
+
+        <para>
+            The default behavior of this task is to run the
+            <filename>oe_runmake</filename> task if a makefile
+            (<filename>Makefile</filename>, <filename>makefile</filename>,
+            or <filename>GNUmakefile</filename>) is found.
+            If no such file is found, the <filename>do_compile</filename>
+            task does nothing.
         </para>
     </section>