VOL-4840 - docs.voltha.org edits

Makefile
patches/python_310_migration.sh
-------------------------------
   o Change log message to note venv patching by version.
   o Original message could be interpreted as explict patching of wrong version.

makefiles/lint/include.mk
-------------------------
   o Document lint targets: usage, commands, makefiles, etc.

Change-Id: I895a0a032f856632c9adf31aa634b6cbf0328cdb
diff --git a/howto/index.rst b/howto/index.rst
index 0a898ec..0167429 100644
--- a/howto/index.rst
+++ b/howto/index.rst
@@ -4,6 +4,7 @@
 .. toctree::
    :maxdepth: 2
 
+   code/index
    edit_voltha_docs
    release/installVoltctl
    voltha_repositories