fix: bug in testing suite + lots of documentation updates

kompendium-playground/build.gradle.kts

@@ -1,6 +1,12 @@
 plugins {
+  kotlin("jvm")
   kotlin("plugin.serialization") version "1.6.10"
-  application
+  id("io.bkbn.sourdough.application.jvm") version "0.5.4"
+  id("application")
+}
+
+sourdough {
+  compilerArgs.set(listOf("-opt-in=kotlin.RequiresOptIn"))
 }
 
 dependencies {

kompendium-playground/src/main/kotlin/io/bkbn/kompendium/playground/util/Util.kt

@@ -6,9 +6,11 @@ import io.bkbn.kompendium.oas.info.Info
 import io.bkbn.kompendium.oas.info.License
 import io.bkbn.kompendium.oas.serialization.KompendiumSerializersModule
 import io.bkbn.kompendium.oas.server.Server
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.json.Json
 import java.net.URI
 
+@OptIn(ExperimentalSerializationApi::class)
 object Util {
   val kotlinxConfig = Json {
     classDiscriminator = "class"