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/Makefile b/Makefile
index 1a86238..a5ca425 100644
--- a/Makefile
+++ b/Makefile
@@ -31,13 +31,13 @@
 
 branch=`cat .gitreview | grep branch | cut -d '=' -f2`
 
+## -----------------------------------------------------------------------
+## -----------------------------------------------------------------------
 help:: # @HELP Print the command options
-	@echo
-	@echo "[TEST]"
 	@echo "  test                          Sanity check chart versions"
 	@echo
 	@echo "[CHECK: release]"
-	@echo "  helm-repo-tools               Repository clone target"
+	@echo "  helm-repo-tools               Helper tools"
 	@echo "  tagcollisionreject.sh         404 - raw.github source MIA"
 	@echo
 	@echo "\033[0;31m    VOLTHA HELM CHARTS \033[0m"
@@ -69,12 +69,21 @@
 test-tags: tagcollisionreject.sh
 	@bash ./tagcollisionreject.sh
 
+## -----------------------------------------------------------------------
+## [NOTE] moving to makefiles/lint/helm/include.mk
+## -----------------------------------------------------------------------
 helm-repo-tools:
 	git clone "https://gerrit.opencord.org/helm-repo-tools"
 
-test: test-tags helm-repo-tools # @HELP Makes sure the versions used in the charts are valid
+## -----------------------------------------------------------------------
+## -----------------------------------------------------------------------
+# test-all += test-tags # tagcollisionreject + curl is broken
+test-all += helm-repo-tools
+test: $(test-all) # @HELP Makes sure the versions used in the charts are valid
 	@COMPARISON_BRANCH=origin/$(branch) ./helm-repo-tools/chart_version_check.sh
 
+## -----------------------------------------------------------------------
+## -----------------------------------------------------------------------
 clean :: # @HELP Removes all files downloaded to run the tests
 	$(RM) -r helm-repo-tools
 	$(RM) tagcollisionreject.*