The generated list of environment variables on http://<jenkins-url>/env-vars.html/ should contain the list of available Git-Env-Vars too, if Git-plugin is installed.
Interesting idea. I had never seen that page before, and don't know how it would be extended to include environment variables available from plugins in various context.
I believe that page only presents the environment variables for bundled plugins.
Descriptions were included in the env-vars.html page by the git plugin beginning with release 3.3.2 July 6, 2017 (a few days after this bug was marked 'Resolved'). My latest change was only an addition to the existing documentation to clarify the non-intuitive values of GIT_AUTHOR_NAME and GIT_AUTHOR_EMAIL.
:) Descriptions were included in the env-vars.html page by the git plugin beginning with release 3.3.2 July 6, 2017 (a few days after this bug was marked 'Resolved'). My [latest change|https://github.com/jenkinsci/git-plugin/pull/732] was only an addition to the existing documentation to clarify the non-intuitive values of GIT_AUTHOR_NAME and GIT_AUTHOR_EMAIL.
Changed help text included in git plugin 3.11.0 released July 27, 2019