Update hello_material.adoc
Update hello_material.adoc

Removed duplication or word common from Default Material Definitions table to space things out some.
jMonkeyEngine/wiki.jmonkeyengine.org,jMonkeyEngine/wiki.jmonkeyengine.org,jMonkeyEngine/wiki.jmonkeyengine.org,jMonkeyEngine/wiki.jmonkeyengine.org