[DOCS] Add upgrade details about stopping ML (elastic/x-pack-elasticsearch#2982)

* [DOCS] Add upgrade details about stopping ML

* [DOCS] Addressed feedback about stopping all ML

Original commit: elastic/x-pack-elasticsearch@1897390edc

docs/en/ml/index.asciidoc

@@ -30,6 +30,7 @@ from {es} for analysis and anomaly results are displayed in {kib} dashboards.
 include::overview.asciidoc[]
 include::getting-started.asciidoc[]
 include::configuring.asciidoc[]
+include::stopping-ml.asciidoc[]
 // include::ml-scenarios.asciidoc[]
 include::api-quickref.asciidoc[]
 //include::troubleshooting.asciidoc[]  Referenced from x-pack/docs/public/xpack-troubleshooting.asciidoc

docs/en/ml/stopping-ml.asciidoc

@@ -0,0 +1,87 @@
+[[stopping-ml]]
+== Stopping Machine Learning
+
+An orderly shutdown of {ml} ensures that:
+
+* {dfeeds-cap} are stopped
+* Buffers are flushed
+* Model history is pruned
+* Final results are calculated
+* Model snapshots are saved
+* Jobs are closed
+
+This process ensures that jobs are in a consistent state in case you want to
+subsequently re-open them.
+
+[float]
+[[stopping-ml-datafeeds]]
+=== Stopping {dfeeds-cap}
+
+When you stop a {dfeed}, it ceases to retrieve data from {es}. You can stop a
+{dfeed} by using {kib} or the
+{ref}/ml-stop-datafeed.html[stop {dfeeds} API]. For example, the following
+request stops the `feed1` {dfeed}:
+
+[source,js]
+--------------------------------------------------
+POST _xpack/ml/datafeeds/feed1/_stop
+--------------------------------------------------
+// CONSOLE
+// TEST[skip:todo]
+
+NOTE: You must have `manage_ml`, or `manage` cluster privileges to stop {dfeeds}.
+For more information, see <<security-privileges>>.
+
+A {dfeed} can be started and stopped multiple times throughout its lifecycle.
+
+For examples of stopping {dfeeds} in {kib}, see <<ml-gs-job1-manage>>.
+
+[float]
+[[stopping-all-ml-datafeeds]]
+==== Stopping All {dfeeds-cap}
+
+If you are upgrading your cluster, you can use the following request to stop all
+{dfeeds}:
+
+[source,js]
+----------------------------------
+POST _xpack/ml/datafeeds/_all/_stop
+----------------------------------
+// CONSOLE
+
+[float]
+[[closing-ml-jobs]]
+=== Closing Jobs
+
+When you close a job, it cannot receive data or perform analysis operations.
+If a job is associated with a {dfeed}, you must stop the {dfeed} before you can
+close the jobs. If the {dfeed} has an end date, the job closes automatically on
+that end date.
+
+You can close a job by using the {ref}/ml-close-job.html[close job API]. For
+example, the following request closes the `job1` job:
+
+[source,js]
+--------------------------------------------------
+POST _xpack/ml/anomaly_detectors/job1/_close
+--------------------------------------------------
+// CONSOLE
+// TEST[skip:todo]
+
+NOTE: You must have `manage_ml`, or `manage` cluster privileges to stop {dfeeds}.
+For more information, see <<security-privileges>>.
+
+A job can be opened and closed multiple times throughout its lifecycle.
+
+[float]
+[[closing-all-ml-datafeeds]]
+==== Closing All Jobs
+
+If you are upgrading your cluster, you can use the following request to close
+all open jobs on the cluster:
+
+[source,js]
+----------------------------------
+POST _xpack/ml/anomaly_detectors/_all/_close
+----------------------------------
+// CONSOLE