install_inno() should be install.inno() from installr

For some reason after I installed remotes and RInno and I ran install_inno() I would get this error:

This version of C:\Users\Matth\AppData\Local\Temp\RtmpW67KpZ\github.com is not compatible with the version of Windows you're running. Check your computer's system information and then contact the software publisher.

Once I ran library(installr) then I ran install_inno() it installed perfectly.

This isn't a huge issue with the documentation, but it could certainly help out the next person who is looking to try to use this package for the first time.