SYSML2_ — Optional language for documentation

Informal specification of requirements is realized as body of the documentation.
Informal requirement specification often contains text formatting and images as illustrations. To facilitate exchange of requirements between different organizations and proper rendering, the used formatting language, the relative root path for included images and their allowed formats have to be aligned.

• add optional 'language' keyword to doc
• define the folder containing the sysml file as root for references made from documentation elements within this file

To provide guidance for users on common formatting

• reference jpg and png as suggested image formats
• reference markdown "md" or other low-complex language as suggested formatting language

example:
requirement def SomeRequirement