I'm getting so used to the M-. plus documentation generation hack that's MGL-PAX, that I use it for all new code which highlighted an issue of with code examples.

The problem is that [the ideally runnable] examples had to live in docstrings. Small code examples presented as verifiable transcripts within docstrings were great, but developing anything beyond a couple of forms of code in docstrings or copy-pasting them from source files to docstrings is insanity or an OOAO violation, respectively.

In response to this, PAX got the INCLUDE locative (see the linked documentation) and became its own first user at the same time. In a nutshell, the INCLUDE locative can refer to non-lisp files and sections of lisp source files which makes it easy to add code examples and external stuff to the documentation without duplication. As always, M-. works as well.