Search 'T' must conform to Encodable and Equatable

[Sherlouk]

While perhaps not always onerous to do, not everybody needs nor wants their documents to conform to Encodable and/or Equatable to perform a simple search using the package.

It may be prudent to look into whether this requirement is necessary, and whether we can get away with simply just T: Decodable instead to make the package as easy to use as possible.