[docs] Documenting that dis is an implementation detail

Hello documenters

From a python-dev thread:

Martin v. Löwis:

The dis module is deliberately (*) not part of the Python language and standard library; it's an implementation detail (as is the func_code attribute, and the code object). [...]

(*) Unfortunately, the documentation fails to mention that, probably because it's too obvious.

Maciej Fijalkowski

Even more, Jython and IronPython don't have Python bytecode at all and they're considered python implementations.

The dis documentation should mention that it’s not authoritative for Python, just a tool for CPython. I may be able to propose a patch this week-end. Do we need to open a bug report to track other mentions of bytecode that fail to mention it’s an implementation detail? Regards