Update Package-quick-reference.rmd

When I setwd() to the R directory I got this error message:

> load_all();
No DESCRIPTION found. Creating with values:

Package: R
Title: 
Description: 
Version: 0.1
Authors@R: # getOptions('devtools.desc.author')
Depends: R (>= 3.0.2)
License: # getOptions('devtools.desc.license')
LazyData: true
Loading R
Invalid DESCRIPTION:
Authors@R field gives no person with author role.
Authors@R field gives no person with maintainer role and email address.

See the information on DESCRIPTION files in section 'Creating R packages' of the 'Writing R Extensions' manual.

Then when I moved up a directory (to the directory that has the DESCRIPTION file) it worked:

> setwd("..")
> load_all();
Loading choroplethr