Minor improvements

Co-Authored-By: Lee de Mora <ledm@pml.ac.uk>

Author: bouweandela

CONTRIBUTING.md

@@ -143,7 +143,7 @@ conda env create -f environment.yml -n esmvaltool_tutorial
 ```
 
 To install the required ruby packages, run the following command in the tutorial's
-main directory to build and serve the website locally.:
+main directory to build and serve the website locally:
 ```bash
 make serve
 ```

environment.yml

@@ -1,7 +1,6 @@
-name: tutorial_short
+name: esmvaltool_tutorial
 channels:
   - conda-forge
-  - defaults
 dependencies:
   - gxx_linux-64
   - rb-nokogiri