document configurable PropertyAccessor arguments
feature #4517 [Reference] document configurable PropertyAccessor arguments (xabbuh)

This PR was merged into the 2.6 branch.

Discussion
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[Reference] document configurable PropertyAccessor arguments

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#11731)
| Applies to    | 2.6+
| Fixed tickets | #4192

Commits
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828ba4d document configurable PropertyAccessor arguments