typos

(From M. Taylor assessment [2022-01-17])

Sec 1: "Fetaures" -> "Features"

Sec 4.2: "A TimeCoords object has ..." -> "A SpectralCoords object has ..."

Sec 5: "The Feature Object is defined ..." -> "The bounding box is defined ..."

Sec 8.2: "used to defined the coordinate" -> "used to define the coordinate"

Appendix A.3: "(see Section 3.1.6)" -> "(see RFC7946 Section 3.1.6)"

Appendix A.4, A.5: There are some illegal trailing commas in the position arrays.