title: What's the difference between Joi.object().keys() and append() methods in terms of adding more keys
body: <p>I have this piece of code</p>
  <pre><code>const baseSchema = Joi.object.keys({
     name: Joi.string().required()
  })
  </code></pre>
  <p>Now I want to add more keys to this schema, I can write</p>
  <pre><code>const basicInfoSchema = baseSchema.keys({
     address: Joi.string().required(),
     phoneNumber: Joi.number().required()
  })
  </code></pre>
  <p>or</p>
  <pre><code>const basicInfoSchema = baseSchema.append({
     address: Joi.string().required(),
     phoneNumber: Joi.number().required()
  })
  </code></pre>
  <p>What's the difference between the two?</p>