Set min-coverage filter to 20 for cle

It doesn't really matter, but for future reference, this doesn't actually need to be quoted (according to the YAML spec). Almost anything but a literal `:` is fine in your keys! 

`blah.yml:`
````yaml
min-coverage.normal:
  min_coverage: 20
  sample_name: normal
````

````ruby
require 'yaml'
YAML.load_file('blah.yml')
=> {"min-coverage.normal"=>{"min_coverage"=>20, "sample_name"=>"normal"}}
````