Update file.rb doc of using a codec to remove syntax error

[jmdoherty]

Extra set of {}s

[elasticsearch-release]

Jenkins standing by to test this. If you aren't a maintainer, you can ignore this comment. Someone with commit access, please review this and clear it for Jenkins to run; then say 'jenkins, test it'.

[jeroenvandevelde]

+1

[wiibaa]

@ph fixed in #44

[ph]

fixed in #44, thanks for the note @wiibaa 🍷