Update fe.md

chapters/fe.md

@@ -27,6 +27,17 @@ Jabba
 curl -sL https://github.com/shyiko/jabba/raw/master/install.sh | bash && . ~/.jabba/jabba.sh
 ```
 
+```
+# list available JDK's
+jabba ls-remote
+
+# install Oracle JDK
+jabba install 1.8
+
+# use 
+jabba use 1.8
+```
+
 图形工具
 ---