Refactor catena4450m101_sensor README.md to put central info centrally

[terrillmoore]

Per the documentation ukaze, we need to pull the info out of here that is not specific to the 4450, and put it someplace central. Then this readme will follow the pattern.

Every sketch needs a README.md explaining (at a minimum):

• what the sketch is intended to do, and when to use it
• which Catenas are supported
• what external hardware is required, and what external hardware is optionally supported
• what libraries are needed
  • how to set up libraries using git-boot.sh (if using git-boot.sh)
  • how to set up libraries from the Arduino environment (if using the environment)
• data format (pointing to extras and the appropriate docs)
• how to provision (pointing to the general instructions) plus any info about platform GUIDs
• how to verify that it's working

[terrillmoore]

As part of #84, the TTN getting started info was centralized. It's not clear that other info can be profitably centralized.

[terrillmoore]

Closed by #85