This is a follow-up of#984 that reformats the "Important Files" section incompiler.rst:

I also found another issue with this section:https://devguide.python.org/internals/compiler/#important-files
In addition to the fact that the listed files don't use any markup, the markup used for most of the files seem incorrect (it's a blockquote due to the indentation). A nested list with full paths for all the files and :cpy-file: should be a better alternative.

In the PR I added links to the files using:cpy-file: and reformatted the list.

Before:

After: