Document spec support

[yschimke]

types.kt has two supported spec versions.

kotlin-sdk/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt

Line 18 in 9341f1e

public const val LATEST_PROTOCOL_VERSION: String = "2024-11-05"

But features like these address newer specs 2025-03-26

#69
#68

It's unclear exactly what is supported, but using with Copilot I get warnings like

Client requested unsupported protocol version 2025-03-26, falling back to 2024-11-05

Could this be documented?