Replace nonsensical word only

Author: ColinDart

part1.asciidoc

@@ -25,7 +25,7 @@ the system _does_; otherwise they'd just use a spreadsheet.
 
 The first part of the book looks at how to build a rich object model
 through TDD (in <<chapter_01_domain_model>>), and then we'll show how
-to keep that model decoupled from technical concerns. We only how to build
+to keep that model decoupled from technical concerns. We show how to build
 persistence-agnostic code and how to create stable APIs around our domain so
 that we can refactor aggressively.