ch_overview.xml: Basic edit and spell check, changed all service names to uppercase, used lists to improve readability, inserted page breaks to force section consistency.
ch_preface.xml: Removed redundant plugin listing, and inserted reference to plugin section.

Change-Id: Ib13ff29f2b09082785dad2b13d8ea65e4fc1c8a0
Merge "ch_overview.xml: Basic edit and spell check, changed all service names to uppercase, used lists to improve readability, inserted page breaks to force section consistency. ch_preface.xml: Removed redundant plugin listing, and inserted reference to plugin section."