Update documentation on ESMValTool module at DKRZ (#1647)

Update install.rst

doc/quickstart/install.rst

@@ -205,9 +205,8 @@ yourself if you are just running diagnostics:
  - CEDA-JASMIN: `esmvaltool` is available on the scientific compute nodes (`sciX.jasmin.ac.uk` where
    `X = 1, 2, 3, 4, 5`) after login and module loading via `module load esmvaltool`; see the helper page at
    `CEDA <https://help.jasmin.ac.uk/article/4955-community-software-esmvaltool>`__ ;
- - DKRZ-Mistral: `esmvaltool` is available on login nodes (`mistral.dkrz.de`) and pre- and post-processing
-   nodes (`mistralpp.dkrz.de`) after login and module loading via `module load esmvaltool`; the command
-   `module help esmvaltool` provides some information about the module.
+ - DKRZ-Levante: `esmvaltool` is available on login nodes (`levante.dkrz.de`) after login and module loading
+   via `module load esmvaltool`; the command `module help esmvaltool` provides some information about the module.
 
 .. note::
     If you would like to use pre-installed versions on HPC clusters (currently CEDA-JASMIN and DKRZ-MISTRAL),