Adding example for kexec (#1558)

fixed an extra space in the command

Fixed the remark

Editorial fixes based on Tanja's suggestion

Additional style fixes

xml/tuning_kexec.xml

@@ -113,7 +113,11 @@
  </sect1>
  <sect1 xml:id="cha-tuning-kexec-internals">
   <title>&kexec; internals</title>
-
+  <remark> ssarkar 07-25-2023:
+   We can reinforce the existing content with material from https://wiki.archlinux.org/title/kexec,
+   especially from the systemd-boot and troubleshooting sections. Perhaps it is better to take it up
+   when writing smart docs on these topics.
+  </remark>
   <para>
    The most important component of &kexec; is the
    <filename>/sbin/kexec</filename> command. You can load a kernel with &kexec;
@@ -189,6 +193,14 @@
    /proc/cmdline) more_options"</replaceable>.
   </para>
 
+  <para>
+   For example, to load the <filename>/boot/vmlinuz-5.14.21-150500.53-default</filename> kernel image
+   with the command line of the currently running production kernel and the
+   <filename>/boot/initrd</filename> file, run the following command:
+  </para>
+<screen>&prompt.root; kexec -l /boot/vmlinuz-5.14.21-150500.53-default \
+ --append="$(cat /proc/cmdline)" --initrd=/boot/initrd</screen>
+
   <para>
    You can always unload the previously loaded kernel. To unload a kernel that
    was loaded with the <option>-l</option> option, use the