move final template to the top

this allows readers to enter the code starting with what is visible from
the outside, instead of working themselves up from purely technical details.

doc/manual/generate-manpage.nix

@@ -7,6 +7,24 @@ let
 
   showCommand = { command, def, filename }:
     let
+      result = ''
+        > **Warning** \
+        > This program is **experimental** and its interface is subject to change.
+
+        # Name
+
+        `${command}` - ${def.description}
+
+        # Synopsis
+
+        ${showSynopsis command def.args}
+
+        ${maybeSubcommands}
+
+        ${maybeDocumentation}
+
+        ${maybeOptions}
+      '';
       showSynopsis = command: args:
         let
           showArgument = arg: "*${arg.label}*" + (if arg ? arity then "" else "...");
@@ -60,24 +78,7 @@ let
             '';
           categories = sort builtins.lessThan (unique (map (cmd: cmd.category) (attrValues options)));
         in concatStrings (map showCategory categories);
-    in squash  ''
-      > **Warning** \
-      > This program is **experimental** and its interface is subject to change.
-
-      # Name
-
-      `${command}` - ${def.description}
-
-      # Synopsis
-
-      ${showSynopsis command def.args}
-
-      ${maybeSubcommands}
-
-      ${maybeDocumentation}
-
-      ${maybeOptions}
-    '';
+    in squash result;
 
   appendName = filename: name: (if filename == "nix" then "nix3" else filename) + "-" + name;