Switch IdGenerator example to PipelineTask/runQuantum.

This better reflects most real-world usage.

python/lsst/meas/base/_id_generator.py

@@ -230,21 +230,25 @@ class IdGenerator:
 
         from lsst.meas.base import DetectorVisitIdGeneratorConfig
         from lsst.pex.config import Config
-        from lsst.pipe.base import Task
+        from lsst.pipe.base import PipelineTask
 
-        class SomeTaskConfig(Config):
+        class SomeTaskConfig(PipelineTaskConfig, ...):
             id_generator = DetectorVisitIdGeneratorConfig.make_field()
 
-        class SomeTask(Task):
+        class SomeTask(PipelineTaskTask):
 
             ConfigClass = SomeTaskConfig
 
             ...
 
-            def run(self, ..., data_id: DataCoordinate):
+            def runQuantum(self, ..., data_id: DataCoordinate):
                 id_generator = self.config.apply(data_id)
                 catalog = id_generator.make_source_catalog(self.schema) ...
 
+    There is no requirement that `IdGenerator` instances be constructed in
+    `PipelineTask.runQuantum` methods and passed to the ``run`` method, but
+    this is the most common approach.
+
     Code that wishes to instead unpack these record IDs to obtain the release
     ID, data ID and counter value should use the same config (often loaded from
     the ``Butler``) and pass a fully-expanded data ID identifying only a