[VOL-5194] - Update repo to use library makefiles.

https://gerrit.opencord.org/plugins/gitiles/onf-make
----------------------------------------------------
This patch will begin replacing the makefiles/ directory (target and logic
duplication) with centrally maintained library makefiles.  repo:onf-make
has been added as a git-submodule.

Simplest patch given the amount of changes needed.
It will only alter where duplicate target logic is included from.

.gitmodules
makefiles/onf-lib
-----------------
  o Checkout repo:onf-make as a submodule of voltha-docs.

makefiles/local/include.mk
--------------------------
  o Add a directory for per-repository makefile targets and overrides.

config.mk
makefiles/config.mk
-------------------
  o Relocate config.mk to avoid cluttering the repository root.

Makefile
--------
 o Replace high level imports with a single library makefile include.

makefiles-orig/virtualenv.mk
----------------------------
  o Help target cleanups, edits will migrate into repo:onf-make
    prior to removal of the local virtualenv.mk makefile.

makefiles/include.mk
--------------------
  o Added new install.mk include used to load onf-lib and local makefiles.
  o Staging: define onf-mk-lib as makefiles-orig/ for now.
  o Legacy makefile cleanup still needed before makefiles/local can be used

howto/index.rst
howto/nop.rst
---------------
  o Cosmetic edit to force a build/license check.
  o Last recheck attempt reported "No Builds Executed".

Depends-On: I7c83bd48d26510e79fd32f8bb97887cace67b55f
Depends-On: If75417c45363ee5c6a514fe9ebd4414ba8cf0cf7
Depends-On: I637d58f3e983b6cb1b7f08d19f16da925a579668

Change-Id: I8d7e53da91e52642726f1c8b997952765cbc1c23
Signed-off-by: Jan Klare <jan.klare@bisdn.de>
diff --git a/howto/nop.rst b/howto/nop.rst
new file mode 100644
index 0000000..ef26f8c
--- /dev/null
+++ b/howto/nop.rst
@@ -0,0 +1,19 @@
+NOP
+===
+
+This file exists purely for side effects.
+
+howto/index.html reference prevents sphinx issuing TOC/not-in-table-of-contents warning.
+
+Modifying comments in this restructuredText(rst) file will force a job to
+run when a status of jenkins "No Builds Executed" is reported.
+
+A compile may not be needed but lint, syntax and license checking normally are.
+
+After "git commit --amend" has updated your patch.
+Visit gerrit and perform a recheck (:ref:`_pull-request-see-also`.)
+
+..
+   [comments: begin]
+   Thu Oct 19 09:22:59 AM EDT 2023
+