anchor.diff:  
   https://developer.github.com/webhooks/creating/[GitHub webhooks] handle the call
   made by GitHub when a repository is updated. When defining the trigger, you must
  -specify a link:../dev_guide/secrets.html[`*secret*`] as part of the URL you supply
  -to GitHub when configuring the webhook. The `*secret*` ensures that only you and
  -your repository can trigger the build. The following example is a trigger
  -definition JSON within the `*BuildConfig*`:
  +specify a `*secret*`, which will be part of the URL you supply to GitHub when
  +configuring the webhook. The secret ensures the uniqueness of the URL, preventing
  +others from triggering the build. The following example is a trigger definition
  +JSON within the `*BuildConfig*`:
   
   ====
   
  
positive.code: Level 1:: Produces basic information about the executed process.
  Level 2:: Produces very detailed information about the executed process.
  Level 3:: Produces very detailed information about the executed process, and a listing of the archive contents.
  Level 4:: Currently produces the same information as level 3. 
  Level 5:: Produces everything mentioned on previous levels and additionally provides docker push messages.
  
  [[source-code]]
  
negative.code: ----
  ====
  
  [NOTE]
  ====
  The secret field in webhook trigger configuration is not the same as `*secret*`
  field you encounter when configuring webhook in GitHub UI. The former is to make
  the webhook URL unique and hard to predict, the latter is an optional string field
  used to create HMAC hex digest of the body, which is sent as an `X-Hub-Signature`
  https://developer.github.com/webhooks/#delivery-headers[header].
  ====
  
  The payload URL is returned as the GitHub Webhook URL by the `describe` command
  (see link:#describe-buildconfig[below]), and is structured as follows:
  
  