Adds Why do you need dotfiles section

.github/README.md

@@ -10,6 +10,7 @@
 ## Contents
 - [Introduction to Dotfiles](#intro)
     - [What are dotfiles?](#what-are-dotfiles)
+    - [Why do you need them?](#why-you-need-a-dotfile-system)
     - [XDG Directories](#xdg-directories)
     - [Containerized Userspace](#containerized-userspace)
     - [Security](#security)
@@ -47,6 +48,14 @@ It's not hard to create your own dotfile repo, it's great fun and you'll learn a
 
 ---
 
+### Why you need a Dotfile System?
+
+By using a dotfile system, you can set up a brand new machine in minutes, keep settings synced across multiple environments, easily roll-back changes, and never risk loosing your precious config files. 
+
+This is important, because as a developer, we usually have multiple machines (work / personal laptops, cloud servers, virtual machines, some GH codespaces, maybe a few Pis, etc). And you're much more productive when working from a familiar environment, with all your settings applied just how you like them. But it would be a pain to have to set each of these machines up manually. Even if you've only got a single device, how much time would you loose if your data became lost or corrupted?
+
+---
+
 ### XDG Directories
 
 The location of most config files can be defined using the [XDG base directory specification](https://specifications.freedesktop.org/basedir-spec), which is honored by most apps. This lets you specify where config, log, cache and data files are stored, keeping your top-level home directory free from clutter. You can do this by setting environmental variables, usually within the [`.zshenv`](https://github.com/Lissy93/dotfiles/blob/master/config/zsh.zshenv) file.