The current example lacks two use statements to be functional.  Additionally the composite index example is wrong, it requires the keys to calculate.
Added missing use statement. Scrapped plain text query for query builder (the original one was missing a where clause too).
Merge pull request #15 from stanlemon/docs-fix

Fix examples
Merge pull request #16 from stanlemon/dbal-fix

Add missing use statement and fix query used in DBALStorage.