Add Decoder#ofDictionaryEntry.

Change-Id: Ie78096e1a7cfd3bcfa446e3ababe15b910d0c23c
diff --git a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Variant.java b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Variant.java
index d1c1049..34d3945 100644
--- a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Variant.java
+++ b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Variant.java
@@ -18,6 +18,7 @@
  *   <li>{@link java.util.Optional} (a GVariant {@code Maybe} type)
  *   <li>{@link java.util.List} (a GVariant array)
  *   <li>{@code Object[]} (a GVariant structure)
+ *   <li>{@link java.util.Map.Entry} (a dictionary entry)
  *   <li>{@link Variant} (a nested variant)
  * </ul>
  *