book: fix typo in Template Syntax page #369

Job	Run time
MSRV	30s
Test (ubuntu-latest, stable)	1m 10s
Audit	20s
Test (ubuntu-latest, beta)	1m 3s
Package (rinja)	48s
Rustfmt	1m 29s
Test (macos-latest, stable)	1m 0s
Package (rinja_actix)	1m 4s
Test (windows-latest, stable)	1m 58s
Package (rinja_axum)	40s
Package (rinja_derive)	28s
Package (rinja_derive_standalone)	1m 2s
Package (rinja_parser)	45s
Package (rinja_rocket)	1m 25s
Package (rinja_warp)	57s
Package (testing)	1m 38s
Package (examples/actix-web-app)	1m 4s
	17m 21s

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