docs: Tweak submitting-patches.rst formatting

The main goal here was to get the subsections to show in the TOC as they do
for all the other documents.  Also call out the DCO in the section title
since it's important.
Reviewed-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/process/submitting-patches.rst

 .. _submittingpatches:
 
-How to Get Your Change Into the Linux Kernel or Care And Operation Of Your Linus Torvalds
-=========================================================================================
+Submitting patches: the essential guide to getting your code into the kernel
+============================================================================
 
 For a person or company who wishes to submit a change to the Linux
 kernel, the process can sometimes be daunting if you're not familiar
@@ -24,10 +24,6 @@ of the mechanical work done for you, though you'll still need to prepare
 and document a sensible set of patches.  In general, use of ``git`` will make
 your life as a kernel developer easier.
 
-Creating and Sending your Change
-********************************
-
-
 0) Obtain a current source tree
 -------------------------------
 
@@ -417,8 +413,8 @@ e-mail discussions.
 
 
 
-11) Sign your work
-------------------
+11) Sign your work — the Developer's Certificate of Origin
+----------------------------------------------------------
 
 To improve tracking of who did what, especially with patches that can
 percolate to their final resting place in the kernel through several
@@ -803,8 +799,8 @@ command like this will do the trick::
   git request-pull master git://my.public.tree/linux.git my-signed-tag
 
 
-REFERENCES
-**********
+References
+----------
 
 Andrew Morton, "The perfect patch" (tpp).
   <http://www.ozlabs.org/~akpm/stuff/tpp.txt>