FileMaker now provides a help file via the Internet.
However you can download a copy and move the folder to your FileMaker app folder. I created an extra folder named help files with a folder for 15 and one for 16.
Click on the icon to open the file in your browser and then copy the url and use it in a script to open your copy rather than going to the Internet.
Open URL: "file:///C:/Program%20Files/FileMaker/FileMaker%20Help/FileMaker%2016%20Help/Resources/index.html"
I make help the #2 script item for full access.
If you use custom menus you can override the one installed with Pro.