Improve QueryBuilder docs

* Remove aliases from examples where they make no sense
* Fixed copy paste error
Merge pull request #659 from JeroenDeDauw/docz

Improve QueryBuilder docs
Fix rst list

The current version is not displayed correctly at
http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/portability.html
Merge pull request #660 from JeroenDeDauw/listfix

Fix rst list
doModifyLimitQuery() was missing an outer "ORDER BY doctrine_rownum"
fixed test cases
Merge branch 'DBAL-940' of https://github.com/mariusklocke/dbal into DBAL-940