Fix opts syntax (see #123)
@ -116,7 +116,7 @@ environment variable, e.g.:
```bash
# This probably should happen in your ~/.{ba|z}shrc
$ export HOMEBREW_CASK_OPTS="/Applications"
$ export HOMEBREW_CASK_OPTS="--appdir=/Applications"
# Installs to /Applications
$ brew cask install a-cask