Merge pull request #127 from hennevogel/bugfix/job-docu

Add missing Active Job documentation

Author: hennevogel

README.md

@@ -132,6 +132,32 @@ Reported tags:
   name:       "Post Load"
 ```
 
+### Active Job
+
+Reported ActiveSupport instrumentation hooks:
+
+- [enqueue.active\_job](https://guides.rubyonrails.org/active_support_instrumentation.html#enqueue-active-job)
+- [perform_start.active\_job](https://guides.rubyonrails.org/active_support_instrumentation.html#perform-start-active-job)
+- [perform.active\_job](https://guides.rubyonrails.org/active_support_instrumentation.html#perform-active-job)
+
+Reported values:
+
+```ruby
+  value: 89.467
+```
+
+Reported tags:
+
+```ruby
+  hook:       ["enqueue", "perform_start", "perform"],
+  state:      ["queued", "running", "succeeded", "failed"],
+  job:        "SomeJobClassName",
+  queue:      "queue_name"
+```
+
+*Note*: Only the measurements with the hook `perform` report a duration in the value.
+The other hooks are counters and always report a value of `1`.
+
 ## Configuration
 
 The only setting you actually need to configure is the name of the database