Update Install.md

Adds steps to install zsh-autosuggestions via Homebrew Formulae.

INSTALL.md

@@ -3,6 +3,7 @@
 * [Packages](#packages)
 * [Antigen](#antigen)
 * [Oh My Zsh](#oh-my-zsh)
+* [HomeBrew](#homebrew)
 * [Manual](#manual-git-clone)
 
 ## Packages
@@ -47,6 +48,21 @@
 
 3. Start a new terminal session.
 
+## Homebrew
+
+1. Install command: 
+    ```sh
+    brew install zsh-autosuggestions
+    ```
+
+2. To activate the autosuggestions, add the following at the end of your .zshrc: 
+    
+    ```sh
+    source $(brew --prefix)/share/zsh-autosuggestions/zsh-autosuggestions.zsh
+    ```
+
+3. Start a new terminal session.
+
 ## Manual (Git Clone)
 
 1. Clone this repository somewhere on your machine. This guide will assume `~/.zsh/zsh-autosuggestions`.