fix: handle fields' multi-line comments

[czeslavo]

If an API type field comment is multi-line, it breaks rendering both Markdown and Asiidoc tables. This PR aims to fix this issue by:

• turning newlines into two break lines (<br />) HTML elements in Markdown renderer,
• turning newlines into hard break lines in Asiidoc renderer.

Should fix #52.

[cla-checker-service]

💚 CLA has been signed

[thbkrkr]

For Asiidoc, I wonder if we could use + or if this could be an issue given that we are in a table?

[czeslavo]

For Asiidoc, I wonder if we could use + or if this could be an issue given that we are in a table?

Yeah, it seems to be working fine. Both HTML and PDF render as expected. 👍 PTAL

[thbkrkr]

Thanks @czeslavo for your contribution!