Add example lesson

_lessons/java-git.md

+---
+title: Java & Git
+---
+
+```
+public class String implements Comparable<String> {
+    ...
+}
+```
+{: overlay="Client" }
+
+Term A
+: Definition A
+
+Term B
+: Definition B.A
+: Definition B.B
+: Definition B.C

_modules/week-01.md

@@ -3,7 +3,7 @@ title: Introduction to Java
 ---
 
 Sep 28
-: [Java & Git](#)
+: [Java & Git]({{ site.baseurl }}{% link _lessons/java-git.md %})
   : [1.1](#)
 
 Sep 29