Update prerequisites.md

prerequisites.md

@@ -3,11 +3,17 @@
 
 ## Essentials
 
-1. **Familiarity with the Linux command line**: we introduced the Linux terminal interface during [Week 1 of the training](https://mmbdtp.github.io/modules/unix/week_1__programme/), but without regular practice these skills are easily lost.
+1. **Familiarity with the Linux command line**: we introduced the Linux terminal interface during [Week 1 of the training](https://mmbdtp.github.io/modules/unix/week_1__programme/)
 2. **A working notebook on CLIMB-BIG-DATA**: each student has a notebook on [CLIMB-BIG-DATA](https://bryn.climb.ac.uk). We will use a notebook for our training
-3. **An account on GitHub**: sign up at [github.com](https://github.com/) to have an account on GitHub
+3. **Install (or update) [Visual Studio Code](https://code.visualstudio.com/)** on your MacBook. You can install the extension for Python.
+4. **Ensure you have the `git`** command in your MacBook terminal. If you type `git --version` and instead of the version you have an error, type `xcode-select --install` and follow the instructions.
+5. **An account on GitHub**: sign up at [github.com](https://github.com/) to have an account on GitHub
+
 
 ## Recommended
 
-1. We will quickly introduce some basics steps of Git and Github. The topic is broad, so you will benefit from watching a [15 minutes introductory video](https://www.youtube.com/watch?v=USjZcfj8yxE&t=1s). You don't need to remember the content.
-2. Python is even broader and again, you should at least watch a [10 minutes intro](https://www.youtube.com/watch?v=fWjsdhR3z3c). You don't need to remember the content.
+1. **Access to Discord**: as we did for the initial training, we can use Discord to quickly share commands, code snippets etc.
+2. We will quickly introduce some basic steps of Git and Github. The topic is broad, so you will benefit from watching a [15-minute introductory video](https://www.youtube.com/watch?v=USjZcfj8yxE&t=1s). You don't need to remember the content.
+3. Python is even broader, and again, you should at least watch a [10-minute intro](https://www.youtube.com/watch?v=fWjsdhR3z3c). You don't need to remember the content.
+
+Note: if you have [brew](https://brew.sh/) and [conda](https://conda.io/projects/conda/en/latest/user-guide/install/macos.html) installed in your local terminal, you can have more fun. But we will not need this during the Masterclass.