Add All The Environment Variables as a zsh til.

README.md

@@ -112,6 +112,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 
 ### zsh
 
+- [All The Environment Variables](zsh/all-the-environment-variables.md)
 - [Cat A File With Line Numbers](zsh/cat-a-file-with-line-numbers.md)
 - [Clear The Screen](zsh/clear-the-screen.md)
 - [Create A File Descriptor with Process Substitution](zsh/create-a-file-descriptor-with-process-substitution.md)

zsh/all-the-environment-variables.md

@@ -0,0 +1,6 @@
+# All The Environment Variables
+
+If you want to see all the environment variables defined on your machine,
+you can list them all out with `printenv`. If you are like me, you probably
+have a ton of them. Pipe it through `less` to make it easier to navigate and
+search through (i.e. `printenv | less`).