minor #169 Update "Version Matrix" section at README.md (phansys)

This PR was merged into the 3.x branch.

Discussion
----------

|Q            |A  |
|---          |---|
|Branch       |3.x|
|Bug fix?     |no |
|New feature? |no |
|BC breaks?   |no |
|Deprecations?|no |
|Tests pass?  |yes|
|Fixed tickets|n/a|
|License      |MIT|
|Doc PR       |n/a|

Commits
-------

aefd6ea Update "Version Matrix" section at `README.md`

Author: phansys

README.md

@@ -88,7 +88,7 @@ I'm open to pull requests for additional languages, features and/or improvements
 [3]: http://getbootstrap.com/docs/3.3/
 [4]: http://symfony.com/blog/new-in-symfony-2-6-bootstrap-form-theme
 [5]: https://symfony.com/doc/current/bundles/FOSUserBundle/index.html
-[6]: https://github.com/hackzilla/TicketBundle/tree/master
+[6]: https://github.com/hackzilla/TicketBundle/tree/3.x
 [7]: https://github.com/hackzilla/TicketBundle/tree/2.x
 [8]: https://github.com/hackzilla/TicketBundle/tree/1.x
 [9]: https://github.com/hackzilla/TicketBundle/tree/0.9.x