Workbench Tools page title

Changed title from "Workbenches" to "Workbench Tools" in order to match
name given in right-hand column and to distinguish it from this page:
http://bladerunnerjs.org/docs/concepts/workbenches/
Fixed link to "Writing Tests" page

Changed 'http://bladerunnerjs.org/docs/use/writing_tests/' to
http://bladerunnerjs.org/docs/use/writing_tests/