[Form] mention "help" field option in UPGRADE file#27393

Merged

nicolas-grekas merged 1 commit intosymfony:4.1from

mhujer:add-form-help-to-upgrade-4.1

May 29, 2018

Commits on May 27, 2018

update UPGRADE-4.1 for feature #26332 Form field help option
mhujer
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