small fix

Author: LisaBock

_episodes/02-installation.md

@@ -59,7 +59,7 @@ in the [documentation](https://docs.esmvaltool.org/en/latest/quickstart/installa
 
 ### Install Mamba
 
-ESMValTool is distributed using [Mamba](https://mamba.readthedocs.io/en/latest/index.html)
+ESMValTool is distributed using [Mamba](https://mamba.readthedocs.io/en/latest/index.html).
 To install mamba on ``Linux`` or ``MacOSX``, follow the  instructions below:
 
 1.  Please download the installation file for the latest Mamba version [here](https://github.com/conda-forge/miniforge#mambaforge).