R_air is named incorrectly

[jensdebruijn]

HydroMT version checks

• [X] I have checked that the issue still exists on the latest versions of the docs on main here

Kind of issue

Docs are wrong

Location of the documentation

https://github.com/Deltares/hydromt/blob/a707d44497ef493174b76fafde90e45085d78a6c/hydromt/workflows/forcing.py#L480

Documentation problem

I believe this should be named the universal gas constant rather than the specific gas constant for dry air. The calculation itself seems correct with the given values.

Suggested fix for documentation

No response