If using the Desired State Configuration File Resource as suggested by @Davidw, I recommend using the Checksum property as well (https://technet.microsoft.com/en-us/library/dn282129.aspx).
If you don't use the Checksum property, the file will never be updated because you're comparing only the file or directory name, which I'm assuming you're not changing when you make edits to the file. Specifying the Checksum property tells DSC to make a change if the SHA-1, SHA-256, SHA-512, createdDate, or modifiedDate is different.
On a related topic, using the single DSC file resource @Davidw recommends will work, but I recommend setting up DSC with a centralized web server so you can manage your files/states from a central distribution point (http://www.systemcentercentral.com/day-1-intro-to-powershell-dsc-and-configuring-your-first-pull-server/). It's easier to manage MOF files from a central point, otherwise you may lose track of the individual MOF file running on each server.
Full disclosure - I develop configuration management software for Windows that solves the above problem, but I also think these steps will work too.