cmake: Move install rule for README, LICENSE

The rule lived in a strange place.  The sources for the installation
rule lived in the directory *above* the rule.

Move the rule from "$TOP/doc/CMakeLists.txt" to "$TOP/CMakeLists.txt".

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
doc: Remove unused file todo.txt

Waffle now uses the issue tracker at
(https://github.com/waffle-gl/waffle/issues).

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
HACKING: Move to hard-to-miss location

Several one-off contributors have submitted patches to Waffle. And they
typically email me directly and send the patches as attachments. Maybe
they didn't bother to read submitting-patches.txt, so let's move it in
a more prominent location.

Rename "/doc/submitting-patches.txt" to "/HACKING.txt". No changes to
file content.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
cmake: Install HACKING alongside README, LICENSE

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
HACKING: Explain better how to send patches

Several one-off contributors have submitted corrupt patches to Waffle as
email attachments.  Improve the HACKING docs to carefully explain how to
do it correctly.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
HACKING: Make advice on commit message style more focused

And add a good example commit message from Emil.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
HACKING: Improve advice on copyright

Make it more simple and more explicit.
List preferred licenses for Waffle: BSD, MIT, Apache 2.0.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
HACKING: Improve section "Sign your work"

Simplify the discussion of Signed-off-by and Developer's Certificate of
Origin.

Pre-patch, HACKING.txt quoted the entirety of Section 12 of the kernel's
Documentation/SubmittingPatches. Linus's writing style, though, is
rambling and unfocused. This patch cleans it up.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
HACKING: Re-order sections

Move "Copyright" to below "Sign you work". Not many people will need to
read the "Copyright" section.

Signed-off-by: Chad Versace <chad@chad-versace.us>
doc/code-style: Shorten and clean up

Concicse is better than rambling. Remove all the nonessential parts of
the file.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Merge branch 'chadv/doc-cleanups'