VOL-4836: Interactive helm chart linting.

repo:voltha-docs job reported reactive post-commit linting errors.
Begin adding support for make target lint-helm for early detection.

Makefile
--------
  o Adding comments for readability.
  o Disable failing/unused targets.
  o Update help text.
  o Migrating some targets and deps from Makefile proper into makefiles/*.

makefiles/README.md
-------------------
  o Added a basic makefile readme with pointers to other web resources.

makefiles/lint/include.mk
makefiles/lint/helm/include.mk
-------------------------
  o Initial support for library makefile target: 'lint-helm'
  o Added common targets: clean, help, sterile and todo.
  o Target 'pre-commit added:
      - default target to support interactive use of lint-helm.
      - Cleanup needed before common target can use lint-helm as a default.
  o Interim answer: briding the gap between existing and portable logic.
  o legacy logic (USE_LEGACY=1 (default)):
      - Relies on .gitreview and hardcoding defaults (opencord/master).
      - git has builtin support for local/remote branch queries.
      - updates to support queries which simplify logic.
  o Interactive target lint-helm-deps
    - Configure helm charts per linting logic in gerrit/jenkins job.
    - Interactive target will invoke make target with USE_LEGACY=$(null).

Change-Id: I43616d16707a09da6f907f909c65504da9933a6f
diff --git a/makefiles/include.mk b/makefiles/include.mk
index e734aeb..aa8c402 100644
--- a/makefiles/include.mk
+++ b/makefiles/include.mk
@@ -24,9 +24,9 @@
 ## -----------------------------------------------------------------------
 help::
 	@echo "USAGE: $(MAKE) [options] [target] ..."
+        # @echo "  test                          Sanity check chart versions"
 
 include $(MAKEDIR)/consts.mk
 include $(MAKEDIR)/lint/include.mk
-include $(MAKEDIR)/variables.mk
 
 # [EOF]