documentation for the ClassMapGenerator class
feature #4081 [Components][ClassLoader] documentation for the ClassMapGenerator class (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[Components][ClassLoader] documentation for the ClassMapGenerator class

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#2471)
| Applies to    | all
| Fixed tickets | #1134

Commits
-------

2ebe6c3 documentation for the ClassMapGenerator class