dev-manual: Review edits applied to selecting init manager section.

Applied comments based on Ross Burton's review of this new section.

(From yocto-docs rev: d4f5f7b712ea2944efffec9b675341143675efb0)

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

documentation/dev-manual/dev-manual-common-tasks.xml

@@ -3771,12 +3771,13 @@
         </para>
 
         <para>
-            If you want to use <filename>SysVinit</filename>, you do
+            If you want to use <filename>sysvinit</filename>, you do
             not have to do anything.
             But, if you want to use <filename>systemd</filename>, you must
             take some steps as described in the following sections.
         </para>
 
+<!--
         <note>
             It is recommended that you create your own distribution configuration
             file to hold these settings instead of using your
@@ -3785,6 +3786,7 @@
             "<link linkend='creating-your-own-distribution'>Creating Your Own Distribution</link>"
             section.
         </note>
+-->
 
         <section id='using-systemd-exclusively'>
             <title>Using systemd Exclusively</title>
@@ -3805,6 +3807,12 @@
                 Doing so removes any redundant <filename>sysvinit</filename>
                 scripts.
             </para>
+
+            <para>
+                For information on the backfill variable, see
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES_BACKFILL_CONSIDERED'><filename>DISTRO_FEATURES_BACKFILL_CONSIDERED</filename></ulink>
+                in the Yocto Project Reference Manual.
+            </para>
         </section>
 
         <section id='using-systemd-for-the-main-image-and-using-sysvinit-for-the-rescue-image'>