Missing variables in documetation

Hello @dbeltran and @bdepaula,

Autosubmit Version

tag:v4.0.0b20

Expid affected

• (general issue)

Summary

Missing documentation

Steps to reproduce

go to https://autosubmit.readthedocs.io/en/latest/userguide/variables.html

What is the current bug behavior?

There is no documentation for SECOND_TO_LAST autosubmit variables, which I need for Destination Earth. I know theses variables exist (cc @bdepaula checked) but there si no docs for them

Relevant logs and/or screenshots(if applicable)

docs

code