anchor.diff:  
   NOTE: By default, Asciidoctor.js will try his best to automatically detect the runtime environment.
   
  -If you want to explicitly define the runtime environment, you can use a `runtime` configuration object when instantiating Asciidoctor.js: 
  -
  -[source,javascript]
  -----
  -const asciidoctor = require('asciidoctor.js')({ 
  +If you want to explicitly define the runtime environment, you can use a `runtime` configuration object when instantiating Asciidoctor.js:
  +
  +[source,javascript]
  +----
  +const asciidoctor = require('asciidoctor.js')({
     runtime: {
  -    platform: 'browser', 
  -    engine: 'v8', 
  +    platform: 'browser',
  +    engine: 'v8',
       framework: 'webextensions'
     }
   });
  
positive.code: 
  Both registry have a `[shout]` block extension registered with a specific implementation.
  
  The first block extension is registered in the `registryA` and will transform the text to uppercase. 
  The other one is registered in the `registryB` and will replace `.` by `{nbsp}!!!`.
  
negative.code: 
  NOTE: By default, Asciidoctor.js will determine the I/O module upon the runtime environment.
  
  If you want to explicitly define the I/O module, you can specify the attribute `runtime.ioModule` when instantiating Asciidoctor.js:
  
  [source,javascript]
  ----
  