minor symfony#11494 Fix incorrect quote (Gun5m0k3)

This PR was submitted for the 4.2 branch but it was merged into the 3.4 branch instead (closes symfony#11494).

Discussion
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Fix incorrect quote

Commits
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f11b797 Update workflow.rst

Author: javiereguiluz

workflow.rst

@@ -431,7 +431,7 @@ transition. The value of this option is any valid expression created with the
                         to:   published
                     reject:
                         # or any valid expression language with "subject" referring to the post
-                        guard: "has_role("ROLE_ADMIN") and subject.isStatusReviewed()"
+                        guard: "has_role('ROLE_ADMIN') and subject.isStatusReviewed()"
                         from: reviewed
                         to:   rejected