zig_0_11: mark as broken

See this error:

The following command exited with code 1:
/build/source/build/stage3/bin/zig test
docgen_tmp/test_noreturn_from_exit.zig -target x86_64-windows
--test-no-exec
../doc/langref.html.in:5198:25: error: test failed
      {#target_windows#}

Generating docgen examples [1872/5411] error: ParseError
/build/source/tools/docgen.zig:1864:17: 0x2a4c5f in exec (docgen)
                return error.ChildExitError;
                ^
/build/source/tools/docgen.zig:289:5: 0x2c023e in parseError__anon_6779
(docgen)
    return error.ParseError;
    ^
/build/source/tools/docgen.zig:1585:29: 0x2b7d4d in genHtml__anon_4842
(docgen)
                            return parseError(tokenizer,
code.source_token, "test failed", .{});
                            ^
/build/source/tools/docgen.zig:106:5: 0x2c44b8 in main (docgen)
    try genHtml(allocator, &tokenizer, &toc, buffered_writer.writer(),
zig_exe, opt_zig_lib_dir, do_code_tests);
    ^

pkgs/development/compilers/zig/generic.nix

@@ -173,6 +173,8 @@ stdenv.mkDerivation (finalAttrs: {
     license = lib.licenses.mit;
     maintainers = with lib.maintainers; [ andrewrk ] ++ lib.teams.zig.members;
     mainProgram = "zig";
+    # docgen fails to build
+    broken = version == "0.11.0";
     platforms = lib.platforms.unix;
   };
 })