main/opensmtpd: fix badly formatted man pages

Fixes http://bugs.alpinelinux.org/issues/7324

main/opensmtpd/APKBUILD

@@ -4,7 +4,7 @@
 # Maintainer: Jonathan Curran <jonathan@curran.in>
 pkgname=opensmtpd
 pkgver=6.0.2p1
-pkgrel=5
+pkgrel=6
 pkgdesc="secure, reliable, lean, and easy-to configure SMTP server"
 url="http://www.opensmtpd.org"
 arch="all"
@@ -40,7 +40,7 @@ build() {
 		--with-libs="-lfts" \
 		--with-pie \
 		--with-path-CAfile=/etc/ssl/certs/ca-certificates.crt \
-		--with-mantype=man
+		--with-mantype=doc
 	make
 }