MAINTAINERS: add crypto-API.tmpl

The file Documentation/DocBook/crypto-API.tmpl documents the kernel
crypto API and is maintained.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

MAINTAINERS

@@ -2805,6 +2805,7 @@ L:	linux-crypto@vger.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6.git
 S:	Maintained
 F:	Documentation/crypto/
+F:	Documentation/DocBook/crypto-API.tmpl
 F:	arch/*/crypto/
 F:	crypto/
 F:	drivers/crypto/