Fixed a php notice for an undefined index
Update basic_example.markdown

the $action->getSubject->getName() is always empty because the $subject was created by action manager in step one and the its $name attribute had never been set.
After tracing source code in Spy\TimelineBundle\Driver\ODM\ActionManager, the effected attribute should be $identifier.
Merge pull request #170 from wingzero0/patch-1

Update basic_example.markdown
Merge pull request #169 from hason/patch-1

Fixed a php notice for an undefined index