Improved a comment
Improved a comment

After going thru and starting to undo some of the last commit, I finally
realised that the "tst" instruction can only test ram locations in zero page,
so changing the flash write-byte routine _back_ to loading an immediate flash
command value -- and testing that from within the OUT service routine --
doesn't work.

I reverted my local changes and decided to commit this change instead.

nickhen/muforth,nickhen/muforth