The example spins too fast so it doesn't appear to change;
it's delaying for microseconds instead of milliseconds.
This commit slows it down and adds a comment noting the pin
mapping for the Adafruit feather rp2040+RFM95 LoRA module,
which has its Neopixel on pin 4 instead of 16.

this removed the RelocatedProgram construction step from pio uses.
there's not all that much to be said for the extra step because the
origin can be set on the input program itself, and the remaining
information exposed by RelocatedProgram can be exposed from
LoadedProgram instead (even though it's already available on the pio_asm
programs, albeit perhaps less convenient). we do lose access to the
relocated instruction iterator, but we also cannot think of anything
this iterator would actually be useful for outside of program loading.

closes #1338