remove duplicate Introduction header from Installation Guide
remove duplicate Introduction header from Installation Guide

Change-Id: Iffa40650cd2c8cd9fbf89f2d23aba6c0619b102a

phillipsio/fuel-docs,ogelbukh/fuel-docs,ogelbukh/fuel-docs,stackforge/fuel-docs,phillipsio/fuel-docs,ogelbukh/fuel-docs,stackforge/fuel-docs,ogelbukh/fuel-docs,phillipsio/fuel-docs,phillipsio/fuel-docs