community/go-md2man: new aport

Adding an explicit go-md2man package, as a number of other packages (runc, containerd, docker, etc.) are building it for the sole purpose of converting markdown documentation to man pages... (often with 'go get', which has raised some unanswered questions.)

community/go-md2man/APKBUILD

+# Contributor: Jake Buchholz <tomalok@gmail.com>
+# Maintainer: Jake Buchholz <tomalok@gmail.com>
+
+pkgname=go-md2man
+pkgver=1.0.8
+pkgrel=0
+pkgdesc="Utility to convert markdown to man pages"
+url="https://github.com/cpuguy83/go-md2man"
+arch="all"
+license="MIT"
+makedepends="go"
+subpackages="$pkgname-doc"
+source="go-md2man-$pkgver.tar.gz::https://github.com/cpuguy83/go-md2man/archive/v$pkgver.tar.gz"
+builddir="$srcdir/src/github.com/cpuguy83/go-md2man"
+
+build() {
+	cd "$srcdir"
+	export GOPATH="$PWD"
+	mkdir -p $(dirname "$builddir")
+	ln -s "$PWD/go-md2man-$pkgver" "$builddir"
+	cd $builddir
+	CGO_ENABLED=0 go build
+}
+
+check() {
+	cd "$builddir"
+	./go-md2man -in go-md2man.1.md -out go-md2man.1
+}
+
+package() {
+	cd "$builddir"
+	install -Dsm755 go-md2man "$pkgdir"/usr/bin/go-md2man
+	install -Dm644 go-md2man.1 "$pkgdir"/usr/share/man/man1/go-md2man.1
+}
+
+sha512sums="4c52e01c9b07582b5d55d1e94935378a676bd284a3e8230a8a191d4678b1b6ae92b704a249117c542832170069a70c649e58a1752fb2973709259b5bc108db91  go-md2man-1.0.8.tar.gz"