Add GHQ_LOOK env variable to a new shell executed by ghq look

[superbrothers]

I want to use the relpath of found local repository on a new shell executed by ghq look.
An example is as follows:

# .zshrc
if [ -n "$GHQ_LOOK" ]; then
    export PROMPT="[$GHQ_LOOK] $PROMPT"
fi

[motemen]

Reasonable. Thank you and sorry for such a late response!

[superbrothers]

Thank you for merge !!