Update remaining mentions of "cross-compilation destinations" to "Swift SDKs"

Not all of the help strings were updated to use "Swift SDK" instead of "cross-compilation destination" after SE-0387 was accepted.

Author: MaxDesiatov

Sources/SwiftSDKTool/Configuration/ConfigureSwiftSDK.swift

@@ -16,7 +16,7 @@ public struct ConfigureSwiftSDK: ParsableCommand {
     public static let configuration = CommandConfiguration(
         commandName: "configuration",
         abstract: """
-        Manages configuration options for installed cross-compilation destinations.
+        Manages configuration options for installed Swift SDKs.
         """,
         subcommands: [
             ResetConfiguration.self,