docs: fix package names (for `cheerpj`, `smetana`)

fix package names on `package-info.java` of `cheerpj` and `smetana`

src/com/plantuml/api/cheerpj/package-info.java

@@ -4,4 +4,4 @@
  * CheerpJ</a> API.
  * 
  */
-package cheerpj;
+package com.plantuml.api.cheerpj;

src/smetana/core/package-info.java

@@ -9,4 +9,4 @@
  * @see net.sourceforge.plantuml.sdot
  * 
  */
-package core;
+package smetana.core;