[DOC] Fix broken link to writing visualizations doc

### What is this PR for?
This PR fixes broken link to doc. Need to be merged branch-0.8.

### What type of PR is it?
Bug Fix

### Questions:
* Does the licenses files need update? no
* Is there breaking changes for older versions? no
* Does this needs documentation? no

Author: Lee moon soo <[email protected]>

Closes #2956 from Leemoonsoo/fix/doc_link_to_helium and squashes the following commits:

9d8cac7 [Lee moon soo] Fix broken link to writing visualizations doc

Author: Leemoonsoo

docs/_includes/themes/zeppelin/_navigation.html

@@ -159,7 +159,7 @@
                 <li><a href="{{BASE_PATH}}/development/helium/overview.html">Overview</a></li>
                 <li><a href="{{BASE_PATH}}/development/helium/writing_application.html">Writing Helium Application</a></li>
                 <li><a href="{{BASE_PATH}}/development/helium/writing_spell.html">Writing Helium Spell</a></li>
-                <li><a href="{{BASE_PATH}}/development/helium/writing_visualization_basics.html">Writing Helium Visualization: Basics</a></li>
+                <li><a href="{{BASE_PATH}}/development/helium/writing_visualization_basic.html">Writing Helium Visualization: Basics</a></li>
                 <li><a href="{{BASE_PATH}}/development/helium/writing_visualization_transformation.html">Writing Helium Visualization: Transformation</a></li>
                 <li role="separator" class="divider"></li>
                 <li class="title"><span>Contributing to Zeppelin</span></li>