Suggestion to improve documentation

[thobach]

Thanks for this great project. I have a few suggestions to improve the documentation to avoid installation errors:

• in the config sample of the readme there is a comma missing at " RefreshInterval: "5000" //milliseconds"
• in the config sample of the readme I believe the variable should be called" RefreshIntervalLAN: "5000" //milliseconds" and not "RefreshInterval"
• in the readme there should be a step that after running git clone the npm install command be run from the MMM-Shelly-PM folder to install "request" dependency that doesn't come with the Magic Mirror app anymore