This PR removes support for NVIDIA Maxwell GPUs (sm50/sm52) in our normal binary distribution. The README and documentation have been updated to reflect this change. There are some other minor corrections to the documentation.

These GPUs are >= 10 years old now. This includes models such as GTX 980, M4, and Quadro M6000. We're making this change as user demand for continued Maxwell support has been very limited, and this will reduce our maintenance and binary size overhead.

For the time being, support for Maxwell GPUs can still be built from source, but we will not continue to guarantee or maintain that compatibility moving forward.

This change is targeted to be included in the upcoming v0.48.0 release.