docs: add `package-info.java` for `gen.annotation` (smetana)

- add `package-info.java` for `gen.annotation`
- add `@see` on `h` and `smetana/core`

src/gen/annotation/package-info.java

@@ -0,0 +1,12 @@
+/**
+ * This package is part of Smetana: 
+ * the internal port (from <code>C</code> to <code>Java</code>) 
+ * of <a href="https://graphviz.org"target="_top">GraphViz/Dot</a> 
+ * in <a href="https://plantuml.com/smetana02" target="_top">plantuml</a>.
+ *
+ * @see h
+ * @see smetana.core
+ * @see net.sourceforge.plantuml.sdot
+ * 
+ */
+package gen.annotation;

src/h/package-info.java

@@ -4,7 +4,18 @@
  * of <a href="https://graphviz.org"target="_top">GraphViz/Dot</a> 
  * in <a href="https://plantuml.com/smetana02" target="_top">plantuml</a>.
  *
+ * <p>
+ * Port of the <code>C header</code> (<code>.h</code>) of Graphviz on Java:
+ * <ul>
+ * <li><code>EN</code> for <code>enumeration</code> or <code>enum</code></li>
+ * <li><code>ST</code> for <code>structure</code></li>
+ * </ul>
+ * </p>
+ * 
  * @see gen
+ * @see gen.annotation
+ * @see gen.lib
+ * @see gen.plugin.dot_layout
  * @see smetana.core
  * @see net.sourceforge.plantuml.sdot
  * 

src/smetana/core/package-info.java

@@ -6,6 +6,9 @@
  *
  * @see h
  * @see gen
+ * @see gen.annotation
+ * @see gen.lib
+ * @see gen.plugin.dot_layout
  * @see net.sourceforge.plantuml.sdot
  * 
  */