Docs improvement: Shut off autosave

[vincemulhollon]

Thanks for writing and supporting this. Your efforts are much appreciated by a very large number of people.

A very small documentation improvement suggestion:

If "file" "Auto Save" is checked, every keystroke will save the source code resulting in CircuitPython restarting the program and rapidly wearing out the flash memory. To avoid this, simply uncheck Auto Save in the "file" menu.

You'll probably want to rephrase the above, I'm not sure exactly where to put it in the docs, etc. But it does solve the problem.

Have a great day!