Fix code block formatting in README and question

[brettz9]

Updated code block formatting in README for clarity.

My real purpose is to ask if you could add Symbol.toStringTag for each of the globals, e.g., GPUCompilationInfo and GPUCompilationMessage, e.g.,

  Object.defineProperty(
      globals.GPUCompilationMessage.prototype, Symbol.toStringTag, {
          get () {
              return 'GPUCompilationMessage';
          }
      }
  );
  Object.defineProperty(
      globals.GPUCompilationInfo.prototype, Symbol.toStringTag, {
          get () {
              return 'GPUCompilationInfo';
          }
      }
  );

For some reason, the string tag is defined only on the constructor, e.g., globals.GPUCompilationMessage, not on its prototype, so objects don't get that.

I don't know if this is something that can be fixed in C source, or whether symbols need to be added in JavaScript.

My interest is to allow structured cloning of these objects, and that requires detection of their type.

Thanks!