minor #3406 [Documentation] Emphase the fact that the include tag outputs data (nstCactus)
minor #3406 [Documentation] Emphase the fact that the include tag outputs data (nstCactus)

This PR was submitted for the 2.x branch but it was merged into the 1.x branch instead.

Discussion
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[Documentation] Emphase the fact that the include tag outputs data

Commits
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ef6debec Emphase the fact that the include tag outputs data

twigphp/Twig,twigphp/Twig,twigphp/Twig