VOL-4840 - Makefile edits

VOL-4874, VOL-4877, VOL-4840

howto/edit_voltha_docs.rst
--------------------------
   * Also need to run "make docs" to generate html content.

Makefile
--------
   * (local use) fixed non-functional makefile targets.
   * Begin splitting monolithic makefile into reusable libs.
   * Extended help to document all targets (make help VERBOSE=1)
   * Extended lint to support more targets.
   * Replace wildcard target (%) with a list of sphinx-build named targets:
     + Amusing behavior but "make clean" should not initiate "gendocs".
     + Likewise "make lint" should not attempt to generate documentation.
   * Introduced simple patching logic for virtualenv.  Local users are
     now able to use make clean, lint, etc with a newer interpreter.
     Baby steps toward VOL-4874.
   * Conditional make vars added:
     + NO_PATCH=1
     + NO_OTHER_REPO_DOCS=1 (venv patching not yet supported by foreign repos).

makefiles/consts.mk
-------------------
   * basic values: space, dot, null, HIDE.

makefiles/help/include.mk
-------------------------
   * makefile target help with context.

makefiles/lint/*.mk
-------------------
   * lib makefiles capturing syntax checking logic.

makefiles/patches/include.mk
----------------------------
   * Targets for creation and applying python virtualenv patches.

patches/*/patch
patches/python_310_migration.sh
-------------------------------
   * Logic used to support dynamic python module pathching in a virtual env directory.
   * Module edits are trivial -- attempt to import new modules and fallback to existing import syntax.

Change-Id: I437289a751423217b4193b75b62c4a295db18ffd
diff --git a/howto/edit_voltha_docs.rst b/howto/edit_voltha_docs.rst
index b63c44f..6a3ba66 100644
--- a/howto/edit_voltha_docs.rst
+++ b/howto/edit_voltha_docs.rst
@@ -27,6 +27,7 @@
    $ make html           # doc generation
    $ make lint           # syntax checking
    $ make test           # syntax check *.rst files
+   $ make docs           # generate website pages
 
    $ "$BROWSER" _build/html/index.html  # BROWSER='firefox'