Update the docs to mention the default serializers

Author: dkhalanskyjb

core/common/src/Instant.kt

@@ -188,6 +188,7 @@ import kotlin.time.*
  * ```
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [Instant]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [InstantIso8601Serializer] for the ISO 8601 extended format.
  * - [InstantComponentSerializer] for an object with components.
  *

core/common/src/LocalDate.kt

@@ -56,6 +56,7 @@ import kotlinx.serialization.Serializable
  * See sample 4.
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [LocalDate]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [LocalDateIso8601Serializer] for the ISO 8601 extended format.
  * - [LocalDateComponentSerializer] for an object with components.
  *

core/common/src/LocalDateTime.kt

@@ -93,6 +93,7 @@ import kotlinx.serialization.Serializable
  * See sample 4.
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [LocalDateTime]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [LocalDateTimeIso8601Serializer] for the ISO 8601 extended format.
  * - [LocalDateTimeComponentSerializer] for an object with components.
  *

core/common/src/LocalTime.kt

@@ -67,6 +67,7 @@ import kotlinx.serialization.Serializable
  * See sample 4.
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [LocalTime]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [LocalTimeIso8601Serializer] for the ISO 8601 extended format,
  * - [LocalTimeComponentSerializer] for an object with components.
  *

core/common/src/UtcOffset.kt

@@ -47,7 +47,8 @@ import kotlinx.serialization.Serializable
  * [parse] and [UtcOffset.format] both support custom formats created with [Format] or defined in [Formats].
  * See sample 3.
  *
- * To serialize and deserialize [UtcOffset] values with `kotlinx-serialization`, use the [UtcOffsetSerializer].
+ * To serialize and deserialize [UtcOffset] values with `kotlinx-serialization`, use the default serializer,
+ * or [UtcOffsetIso8601Serializer] for explicit ISO 8601 format.
  *
  * @sample kotlinx.datetime.test.samples.UtcOffsetSamples.construction
  * @sample kotlinx.datetime.test.samples.UtcOffsetSamples.simpleParsingAndFormatting