macOS Installation

[Alex]

Hi guys! I managed to run it on macOS, it would be nice to add the instrucions into the README.md.

Installation:

1. Dependancies

   brew install pup
   brew install imagemagick  # for .pdf support
   brew install zathura  # don't forget to follow the set up instructions (brew will guide you)
   brew install zathura-cb  # don't forget to follow the set up instructions (brew will guide you)
   bew install bash  # plugin requires new version of bash 4.xx, while macOS uses 3.xx

2. Install the plugin. It is the same as with Linux

   git clone https://github.com/prsh11/manga-cli.git && cd manga-cli
   sudo cp manga-cli /usr/local/bin/manga-cli