Add packages resources (#1619)

* Update 106-packages.md

* Update content/roadmaps/110-java/content/100-java-fundamentals/106-packages.md

Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

content/roadmaps/110-java/content/100-java-fundamentals/106-packages.md

@@ -1 +1,3 @@
 # Packages
+
+A package is a namespace that mainly contains classes and interfaces. For instance, the standard class `ArrayList` is in the package `java.util`. For this class, `java.util.ArrayList` is called its fully qualified name because this syntax has no ambiguity. Classes in different packages can have the same name. For example, you have the two classes `java.util.Date` and `java.sql.Date`, which are different. If no package is declared in a class, its package is the default package.