Integration edits for repo:voltha-docs use.

This patch will add makefile targets and exclusions for doc8 (estructuredText) linting.

makefiles/lint/doc8/excl.mk
makefiles/lint/doc8/doc8.mk
makefiles/lint/doc8/help.mk
makefiles/lint/doc8/include.mk
makefiles/lint/doc8/install.mk
------------------------------
  o Apply exclusion list so checking will not fail on python venv dirs.
  o Split include.mk into named modular makfiles.

makefiles/lint/include.mk
makefiles/lint/shell.mk
-------------------------
  o Remove legacy shell.mk config, lint target loads from lint/shell/*.

Change-Id: I8c214dc499356edf9778ae7ec1deeddf35bd3b65
diff --git a/makefiles/lint/include.mk b/makefiles/lint/include.mk
index be19569..2a004af 100644
--- a/makefiles/lint/include.mk
+++ b/makefiles/lint/include.mk
@@ -40,7 +40,7 @@
 include $(ONF_MAKEDIR)/lint/license/include.mk
 include $(ONF_MAKEDIR)/lint/makefile.mk
 include $(ONF_MAKEDIR)/lint/python/include.mk
-include $(ONF_MAKEDIR)/lint/shell.mk
+include $(ONF_MAKEDIR)/lint/shell/include.mk
 include $(ONF_MAKEDIR)/lint/tox/include.mk
 include $(ONF_MAKEDIR)/lint/yaml/include.mk