Merge branch 'hotfix/#1285-zend-code-generator-headlines'

Close #1285
Merge branch 'hotfix/#1284-user-guide/wrong-filename'

Close #1284
Fix headlines in Zend\Test\PHPUnit chapter

Another small step for consistency in structure of docs
Merge branch 'hotfix/#1286-zend-test-docs-headlines' into develop

Close #1286
Forward Port #1286