docs(metrics): reference PeriodicExportingMetricReader usage with push exporters (open-telemetry#4942)

* docs(metrics): reference PeriodicExportingMetricReader usage with push exporters

* docs(metrics): reorder examples to match argument order

Author: chimchim89

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/__init__.py

@@ -377,13 +377,25 @@ class MeterProvider(APIMeterProvider):
         metric_readers: Register metric readers to collect metrics from the SDK
             on demand. Each :class:`opentelemetry.sdk.metrics.export.MetricReader` is
             completely independent and will collect separate streams of
-            metrics. TODO: reference ``PeriodicExportingMetricReader`` usage with push
-            exporters here.
+            metrics. For push-based export, use
+            :class:`opentelemetry.sdk.metrics.export.PeriodicExportingMetricReader`.
         resource: The resource representing what the metrics emitted from the SDK pertain to.
         shutdown_on_exit: If true, registers an `atexit` handler to call
             `MeterProvider.shutdown`
         views: The views to configure the metric output the SDK
 
+    .. code-block:: python
+        :caption: Push-based export with PeriodicExportingMetricReader
+
+        from opentelemetry.sdk.metrics import MeterProvider
+        from opentelemetry.sdk.metrics.export import (
+            ConsoleMetricExporter,
+            PeriodicExportingMetricReader,
+        )
+
+        reader = PeriodicExportingMetricReader(ConsoleMetricExporter())
+        provider = MeterProvider(metric_readers=[reader])
+
     By default, instruments which do not match any :class:`opentelemetry.sdk.metrics.view.View` (or if no :class:`opentelemetry.sdk.metrics.view.View`\ s
     are provided) will report metrics with the default aggregation for the
     instrument's kind. To disable instruments by default, configure a match-all