Update Javadocs with @snippet blocks.

Change-Id: Id28c226b6882c088f288b247f73041be807be862
diff --git a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java
index 8a3741b..2cb36c6 100644
--- a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java
+++ b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java
@@ -40,7 +40,7 @@
  * <p>To parse a GVariant of type {@code "a(si)"}, which is an array of pairs of {@link String} and
  * {@code int}, you can use the following code:
  *
- * <pre>{@code
+ * {@snippet lang="java" :
  * record ExampleRecord(String s, int i) {}
  *
  * var decoder =
@@ -50,9 +50,9 @@
  *       Decoder.ofString(UTF_8),
  *       Decoder.ofInt().withByteOrder(LITTLE_ENDIAN)));
  *
- * byte[] bytes = ...;
+ * byte[] bytes;
  * List<ExampleRecord> example = decoder.decode(ByteBuffer.wrap(bytes));
- * }</pre>
+ * }
  *
  * @param <T> the type that the {@link Decoder} can decode.
  */
diff --git a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/package-info.java b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/package-info.java
index a1e0a20..e2e8143 100644
--- a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/package-info.java
+++ b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/package-info.java
@@ -14,7 +14,7 @@
  * <p>To parse a GVariant of type {@code "a(si)"}, which is an array of pairs of {@link
  * java.lang.String} and {@code int}, you can use the following code:
  *
- * <pre>{@code
+ * {@snippet lang="java" :
  * record ExampleRecord(String s, int i) {}
  *
  * var decoder =
@@ -24,8 +24,8 @@
  *       Decoder.ofString(UTF_8),
  *       Decoder.ofInt().withByteOrder(LITTLE_ENDIAN)));
  *
- * byte[] bytes = ...;
+ * byte[] bytes;
  * List<ExampleRecord> example = decoder.decode(ByteBuffer.wrap(bytes));
- * }</pre>
+ * }
  */
 package eu.mulk.jgvariant.core;
diff --git a/jgvariant-core/src/main/java/module-info.java b/jgvariant-core/src/main/java/module-info.java
index 4df8acd..6b45af0 100644
--- a/jgvariant-core/src/main/java/module-info.java
+++ b/jgvariant-core/src/main/java/module-info.java
@@ -26,7 +26,7 @@
  *
  * <h3 id="sect-installation-maven">Usage with Maven</h3>
  *
- * <pre>{@code
+ * {@snippet lang="xml" :
  * <project>
  *   ...
  *
@@ -63,21 +63,21 @@
  *
  *   ...
  * </project>
- * }</pre>
+ * }
  *
  * <h3 id="sect-installation-gradle">Usage with Gradle</h3>
  *
- * <pre>{@code
+ * {@snippet lang="groovy" :
  * dependencies {
- *   ...
+ *   // ...
  *
- *   implementation(platform("eu.mulk.jgvariant:jgvariant-bom:0.1.5")
+ *   implementation(platform("eu.mulk.jgvariant:jgvariant-bom:0.1.5"))
  *   implementation("eu.mulk.jgvariant:jgvariant-core")
  *   implementation("eu.mulk.jgvariant:jgvariant-ostree")
  *
- *   ...
+ *   // ...
  * }
- * }</pre>
+ * }
  */
 module eu.mulk.jgvariant.core {
   requires com.google.errorprone.annotations;
diff --git a/jgvariant-ostree/src/main/java/module-info.java b/jgvariant-ostree/src/main/java/module-info.java
index 6e6018e..18daf94 100644
--- a/jgvariant-ostree/src/main/java/module-info.java
+++ b/jgvariant-ostree/src/main/java/module-info.java
@@ -25,7 +25,7 @@
  *
  * <h3 id="sect-installation-maven">Usage with Maven</h3>
  *
- * <pre>{@code
+ * {@snippet lang="xml" :
  * <project>
  *   ...
  *
@@ -62,21 +62,21 @@
  *
  *   ...
  * </project>
- * }</pre>
+ * }
  *
  * <h3 id="sect-installation-gradle">Usage with Gradle</h3>
  *
- * <pre>{@code
+ * {@snippet lang="groovy" :
  * dependencies {
- *   ...
+ *   // ...
  *
- *   implementation(platform("eu.mulk.jgvariant:jgvariant-bom:0.1.5")
+ *   implementation(platform("eu.mulk.jgvariant:jgvariant-bom:0.1.5"))
  *   implementation("eu.mulk.jgvariant:jgvariant-core")
  *   implementation("eu.mulk.jgvariant:jgvariant-ostree")
  *
- *   ...
+ *   // ...
  * }
- * }</pre>
+ * }
  */
 module eu.mulk.jgvariant.ostree {
   requires transitive eu.mulk.jgvariant.core;