Update About page for version 3.1.0

[john-shepherdson]

Version number and release date

[matthew-morris-cessda]

Any example text, or do you just want the version number and release date changed?

[john-shepherdson]

I don't think there any user-facing changes, so just version number and date.

[john-shepherdson]

Maja has said that no changes are required to contents of either User Guide or Editors Guide

[john-shepherdson]

Has this been done?

[matthew-morris-cessda]

Not yet. I was going to release the code first, then update the about page.

[john-shepherdson]

version 3.1.0, released on 2023-04-04

[matthew-morris-cessda]

About page updated