Update readme

README.md

@@ -7,7 +7,7 @@ We are using `mkdocs` as the static site generator to generate the website from
 
 You can preview the website after cloning it. First you need to install `mkdocs` and the used theme by:
 ```sh
-pip install mkdocs mkdocs-material mkdocs-glightbox mkdoxy mkdocs-site-urls
+pip install mkdocs mkdocs-material mkdocs-glightbox mkdoxy mkdocs-site-urls mkdocs-bibtex
 ```
 
 Then you can change the directory to the repository and run