These guides are inteded to be easily viewable on a mobile phone. While you can certainly bookmark this website and use it as-is, it may be easier to save each synth that you are actually using as a separate link on your phone's home screen.
Navigate to the synth's page, then follow the instructions at the links that follow. For iPhone follow these instructions, and for Android follow these.
You'll then have icons on your phone that launch the individual synth's page. They should work even if your phone is not connected to the internet. Note that doing this will not pick up changes I may make, so be sure to click “Refresh Content” from time-to-time.