fill changelog and add kdocs for firstOf

tgbotapi.core/src/commonMain/kotlin/dev/inmo/tgbotapi/utils/FirstOf.kt

@@ -3,6 +3,18 @@ package dev.inmo.tgbotapi.utils
 import dev.inmo.micro_utils.coroutines.firstOf
 import kotlinx.coroutines.CoroutineScope
 
+/**
+ * Launches all provided suspending [deferreds] in this [CoroutineScope] and returns the value
+ * produced by the first block that completes.
+ *
+ * - Provide at least one block; otherwise the call will never complete.
+ * - Cancellation and error propagation semantics are delegated to the underlying
+ *   dev.inmo.micro_utils.coroutines.firstOf implementation.
+ *
+ * @param T The type of the resulting value.
+ * @param deferreds The suspending blocks to race; they are started eagerly.
+ * @return The result produced by the first completed block.
+ */
 suspend fun <T> CoroutineScope.firstOf(
     vararg deferreds: suspend () -> T
 ): T = firstOf {