GitLab

Added instructions for installing zsh (due to the problems with first time zsh users)

The wiki is more readable than going to the plugins directory.

Uses environment variable $ZSH to configure install location.

Add upgrade command to docs. I canceled the prompt once and went hunting for this so I could upgrade.

The wiki is more readable than going to the plugins directory.

Updating installation documentation to show a curl example as well for those who don't have wget installed.

github uses a wildcard certificate which is not accepted by wget