Fix lists format

[hablutzel1]

PDFs are generated with pandoc, and according to
https://pandoc.org/MANUAL#paragraphs , it requires a blank line at the end of paragraphs:

A paragraph is one or more lines of text followed by one or more blank lines.

Missing to provide such blank line before a list renders like this:

While the correct presentation is:

PS: Other cabforum documents in different repositories might require this fix as well, but I didn't check.

[hablutzel1]

The PR at cabforum/build-guidelines-action#51 brings a definitive solution to this problem.