Missing (optional?) dependency asciidoctor

Description:

Some actions within freecad require the asciidoctor package and throw an exception when it cannot be found.

Additional info:

• package version(s): 0.21.2-6 (but also 0.21.2-13)
• config and/or log files:
• link to upstream bug report, if any:

Steps to reproduce:

1. Install freecad but not asciidoctor
2. Open freecad
3. Open the Path workbench
4. Create a new path
5. Click on post processing for that path (the icon one to the right of the create one)
6. Now an exception is thrown.
7. Repeat with asciidoctor installed and it now works.