Add Declared in field to the docs with link to the source on github

Author: thelegy

docs/docs.nix

@@ -64,6 +64,7 @@ with lib; let
     ];
     codeBlock = code: "```\n${code}\n```";
     fieldName = name: "<div class=\"fieldname\">${name}</div>\n";
+    modulePath = path: head (strings.match "/nix/store/[^/]+/(.*)" path);
     renderOptionDoc = name: option: ''
       ### ${escapeXML name}
 
@@ -90,6 +91,14 @@ with lib; let
         ${renderCode option.example}
       ''}
 
+
+      ${fieldName "Declared in"}
+      ${flip concatMapStrings option.declarations (x: ''
+
+        <a href="https://github.com/${owner}/${repo}/blob/main/${modulePath x}" target="_blank">${modulePath x}</a>
+
+      '')}
+
       </div>
     '';
   in (mapAttrs renderOptionDoc optionsDocParsed);