Add zsh installation examples and reorganise the section

Installing-ZSH.md

@@ -7,14 +7,14 @@ Oh-My-Zsh is a framework for [Zsh](http://www.zsh.org), the Z shell.
   - Expected result: `zsh 4.3.9` or more recent
 - Additionally, Zsh should be set as your default shell.
   - Please run `echo $SHELL` from a new terminal to confirm.
-  - Expected result: `/bin/zsh`
+  - Expected result: `/bin/zsh` or similar
 
-## Installing Zsh
+## Install and set up zsh as default
 
 If necessary, follow these steps to install Zsh:
 
 1. There are two main ways to install Zsh
-  - with the package manager of your choice (_e.g._ `sudo apt-get install zsh`) or
+  - with the package manager of your choice, _e.g._ `sudo apt-get install zsh` (see [below for more examples](#howto-install-zsh-in-many-platforms))
   - from [source](http://zsh.sourceforge.net/Arc/source.html), following
         [instructions from the Zsh FAQ](http://zsh.sourceforge.net/FAQ/zshfaq01.html#l7)
 2. Verify installation by running `zsh --version`. Expected result: `zsh 4.3.9` or more recent.
@@ -22,4 +22,50 @@ If necessary, follow these steps to install Zsh:
   - Note that this will not work if Zsh is not in your authorized shells list (`/etc/shells`)
     or if you don't have permission to use `chsh`. If that's the case [you'll need to use a different procedure](https://www.google.com/search?q=zsh+default+without+chsh).
 4. Log out and login back again to use your new default shell.
-5. Test that it worked with `echo $SHELL`. Expected result: `/bin/zsh`
+5. Test that it worked with `echo $SHELL`. Expected result: `/bin/zsh` or similar.
+
+## HowTo install zsh in many platforms
+
+### macOS
+
+```sh
+brew install zsh zsh-completions
+```
+
+Assuming you have [Homebrew](http://brew.sh/) installed. If not, most versions of
+**macOS** ship zsh by default, but it's normally an older version.
+
+**Try `zsh --version` before installing it from Homebrew. If it's newer than 4.3.9
+you _might_ be OK. Preferably newer than or equal to 5.0 **
+
+### Ubuntu, Debian & derivatives
+
+```sh
+apt install zsh
+```
+
+If you don't have `apt`, the recommended package manager for end users
+[[1]](http://askubuntu.com/a/446484)
+[[2]](http://askubuntu.com/a/775264)
+[[3]](https://help.ubuntu.com/lts/serverguide/apt.html)
+[[4]](http://www.howtogeek.com/234583/simplify-command-line-package-management-with-apt-instead-of-apt-get/)
+, you can try `apt-get` or `aptitude`.
+
+[Other distributions that apply](https://en.wikipedia.org/wiki/List_of_Linux_distributions#Debian-based) include:
+Linux Mint, elementary OS, Zorin OS.
+
+### OpenSUSE
+
+```sh
+zypper install zsh
+```
+
+### Arch Linux
+
+```sh
+pacman -S zsh
+```
+
+### Add yours
+
+If you know a platform that is not covered, edit this page and add it!