Apply suggestion to docs/installation_instructions.md

docs/installation_instructions.md

@@ -33,7 +33,8 @@ open an issue on:
     data;
   * root ssh access.
 * A trusted local machine to run the installer on:
-  * You need Python 3 and [virtualenv](https://virtualenv.pypa.io/en/stable/) to
+  * Python 3 installed
+  * We recommend using a [python virtual env](https://docs.python.org/3/tutorial/venv.html) to
     make sure we do not change any of your other projects. Install virtualenv
     by running `pip3 install --user virtualenv` or `apt install virtualenv`