minor #2040 [Doc] Updated some article for Symfony 4 (javiereguiluz)
minor #2040 [Doc] Updated some article for Symfony 4 (javiereguiluz)

This PR was squashed before being merged into the 1.17.x-dev branch (closes #2040).

Discussion
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[Doc] Updated some article for Symfony 4

This fixes #1993.

Commits
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dbb948a [Doc] Updated some article for Symfony 4

yceruto/EasyAdminBundle,javiereguiluz/EasyAdminBundle,OskarStark/EasyAdminBundle,OskarStark/EasyAdminBundle,yceruto/EasyAdminBundle,yceruto/EasyAdminBundle,javiereguiluz/EasyAdminBundle,OskarStark/EasyAdminBundle