Documentation update

Minor update to STRAVVS v2.0 documentation to add Zenodo DOI.

2026 release of STRAVVS

This is an updated release of STRAVVS as at 15 September 2026.

2025 release of STRAVVS NetLogo code

Though not actually 'released' at that time, this is the '2025' release of STRAVVS that is being done on 15 September 2026 prior to a 'proper' release of STRAVVS, for the purpose of preserving this version of the code, which at the time of release has in fact been the subject of several revisions.