added space to internal comment
documented defaults for units and symbols
fetch_cmd variable already set in line-39.
standardize icon key style
Merge pull request #42 from royhodgman/doc

small documentation changes
Merge pull request #44 from thirota/fix-config-sample

standardize icon key style
Merge pull request #43 from thirota/onetime-fetch_cmd

fetch_cmd variable already set in line-39.