add description for the `validation_groups` option
change misleading language identifier
changed dash to underscore
formatting to follow 72 characters line limit
bug #4284 change misleading language identifier (Kristof Van Cauwenbergh, kristofvc)

This PR was merged into the 2.3 branch.

Discussion
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change misleading language identifier

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets | #4251

Commits
-------

db85c67 formatting to follow 72 characters line limit
12cccc8 changed dash to underscore
d68cd09 change misleading language identifier
feature #4246 [Reference] add description for the `validation_groups` option (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[Reference] add description for the `validation_groups` option

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#6528)
| Applies to    | all
| Fixed tickets | #3358

Commits
-------

c41b17c add description for the `validation_groups` option
Merge branch '2.3' into 2.5

* 2.3:
  formatting to follow 72 characters line limit
  changed dash to underscore
  change misleading language identifier
  add description for the `validation_groups` option