Added file structure documentation for zsh.

zsh/README.md

@@ -0,0 +1,38 @@
+
+# ZSH
+
+## File Structure.
+
+The file structure looks something like this: Nodes with a trailing "δ" are directories. 
+
+```
+zsh
+├── environment δ 
+│   ├── host δ
+│   └── os δ
+│       ├── darwin δ
+│       └── linux-gnu δ
+├── makefile
+├── modules δ
+├── transient δ
+├── zlogin
+├── zlogout
+├── zplug
+├── zprofile
+├── zshenv
+└── zshrc
+```
+
+* `environment` :: This is the contains environment base logic and contains. At
+  each step of the zsh loading process the `env_loader` function will load the
+  corresponding file.
+  * `host` :: Loaded Automatically. Conditionally loads by based on `$HOST` value.
+  * `os` :: Loaded Automatically. Conditionally loads by based on `$OSTYPE` value.
+* `makefile` :: Install/Update/Remove makefile. 
+* `modules` :: Local modules loaded by [zplug](https://github.com/zplug/zplug).
+* `transient` :: Files that are required for zsh (eg history), that are not to
+  be versioned.
+* `zlogin`/`zlogout`/`zprofile`/etc :: The default shell resource files. See
+  [here](https://shreevatsa.wordpress.com/2008/03/30/zshbash-startup-files-loading-order-bashrc-zshrc-etc/)
+  for more infomation on load order.
+* `zplug` :: How to load modules.