Update authors list, prepare for v4.0

AUTHORS

@@ -5,5 +5,11 @@ forming a part of the annual CoDiMa Training Schools in Computational
 Discrete Mathematics (https://blogs.cs.st-andrews.ac.uk/codima/training/).
 The development has been supported by the CoDiMa CCP (EP/M022641/1).
 
+Further authors from the GAP community are:
+- Michael Young
+- Christopher Jefferson
+- Max Horn
+- James Mitchell
+
 The template for Software Carpentry lessons has its own list of authors
 available at https://github.com/swcarpentry/styles/graphs/contributors.

CITATION

@@ -1,6 +1,7 @@
 Please cite as:
 
-Olexandr Konovalov, Michael Young, Christopher Jefferson et al.,
-Programming with GAP: Carpentries Incubator lesson, Version 3.1,
-February 2023 (https://carpentries-incubator.github.io/gap-lesson/).
+Olexandr Konovalov, Michael Young, Christopher Jefferson,
+Max Horn, James Mitchell et al.,
+Programming with GAP: Carpentries Incubator lesson, Version 4.0,
+August 2024 (https://carpentries-incubator.github.io/gap-lesson/).
 Zenodo, https://doi.org/10.5281/zenodo.597073.

README.md

@@ -6,7 +6,7 @@ Its development was started by Olexandr Konovalov for the Software Carpentry
 workshop organised as a part of the [First CoDiMa Training School in Computational
 Discrete Mathematics](https://blogs.cs.st-andrews.ac.uk/codima/school2015/) in 2015. Since then, it
 has had several releases, produced in collaboration with further contributors, and has
-been taught by different instructors at more than ten different events, the full list
+been taught by different instructors at least fifteen events, the full list
 of which is available on the GAP lesson wiki
 [here](https://github.com/carpentries-incubator/gap-lesson/wiki).
 
@@ -37,5 +37,3 @@ EP/M022641/1 and from the [OpenDreamKit](https://opendreamkit.org/)
 [Horizon 2020](https://ec.europa.eu/programmes/horizon2020/)
 [European Research Infrastructures](https://ec.europa.eu/programmes/horizon2020/en/h2020-section/european-research-infrastructures-including-e-infrastructures)
 project (#<a href="https://cordis.europa.eu/project/rcn/198334_en.html">676541</a>).
-
-