generate asciidoc.conf via autoconf

…instead of updating it in release.sh.

man/asciidoc.conf.in

@@ -0,0 +1,18 @@
+ifdef::doctype-manpage[]
+ifdef::backend-docbook[]
+[header]
+template::[header-declarations]
+<refentry>
+<refmeta>
+<refentrytitle>{mantitle}</refentrytitle>
+<manvolnum>{manvolnum}</manvolnum>
+<refmiscinfo class="source">i3</refmiscinfo>
+<refmiscinfo class="version">@PACKAGE_VERSION@</refmiscinfo>
+<refmiscinfo class="manual">i3 Manual</refmiscinfo>
+</refmeta>
+<refnamediv>
+  <refname>{manname}</refname>
+  <refpurpose>{manpurpose}</refpurpose>
+</refnamediv>
+endif::backend-docbook[]
+endif::doctype-manpage[]