Update reference to SDC-00

See merge request !27

And versions for some released documents.

 This would make the list comprehension generate an empty string only.
 Added an if statement to only parse the tag if it actually contains any
text.

 To make it more generic

Clever references

See merge request swinbank/astron-texmf!22

Add more abbreviations

See merge request swinbank/astron-texmf!21