Updated README

README.md

@@ -19,4 +19,6 @@ source venv/bin/activate
 pip install -r requirements.txt
 ```
 
+Snakemake should be installed on the side.
+
 You can then run `snakemake -c4` to download PDF files and extract their contents. PDF files are stored in `./pdfs`, and textual contents in ` ./txts/`.