Improved the overall documentation for the public and internal types in the package.

Sources/AmiiboService/Internal/Transcoders/ISOTimestampTranscoder.swift

@@ -31,10 +31,16 @@ extension ISOTimestampTranscoder: DateTranscoder {
     
     // MARK: Functions
     
+    /// Encodes a date into an ISO timestamp string.
+    /// - Parameter date: A date to encode.
+    /// - Returns: A string representation of the date in `yyyy-MM-dd'T'HH:mm:ss.SSSSSS` format.
     func encode(_ date: Date) throws -> String {
         dateFormatter.string(from: date)
     }
     
+    /// Decodes an ISO timestamp string into a date.
+    /// - Parameter string: A string to decode.
+    /// - Returns: A date parsed from the string, or the Unix epoch if the string cannot be parsed.
     func decode(_ string: String) throws -> Date {
         dateFormatter.date(from: string) ?? .init()
     }