use correct package name for opencv

README.md

@@ -5,12 +5,26 @@ of what sauron-cv seeks to accomplish.
 
 ## Installation
 
+It is strongly recommended that you use a virtual environment. These instructions will assume you are using venv, you
+can substitute this with your preferred environment management. You will need to make sure that the `virtualenv` package
+is installed globally, either via pip or the `python3-virtualenv` package in your system package manager.
+
+When first cloning this repo, run the following:
+
 ```shell
 python -m venv .venv
 source .venv/bin/activate
 pip install -r requirements.txt
 ```
 
+This will create a virtual environment, enter that virtual environment, and install the required packages.
+
+If you start a new shell, you will need to re-enter the virtual environment:
+
+```shell
+source .venv/bin/activate
+```
+
 ## Running
 
 ### Client

requirements.txt

@@ -1,2 +1,2 @@
-opencv
+opencv-python
 numpy