[DOCS] Add xpack.ml.max_model_memory_limit (elastic/x-pack-elasticsearch#2787)

* [DOCS] Add xpack.ml.max.model_memory_limit

* [DOCS] Addressed feedback on model limit setting

Original commit: elastic/x-pack-elasticsearch@77a10bfe0e

docs/en/rest-api/ml/jobresource.asciidoc

@@ -325,14 +325,22 @@ For more information, see
   This value will need to be increased for jobs that are expected to analyze high
   cardinality fields, but the default is set to a relatively small size to ensure
   that high resource usage is a conscious decision. The default value for jobs
-  created in versions earlier than 6.1 is `4096mb`. If you specify a number instead
-  of a string, the units are assumed to be MiB. Specifying a string is recommended
-  for clarity. If you specify a byte size unit of `b` or `kb` and the number
-  does not equate to a discrete number of megabytes, it is rounded down to the
-  closest MiB. The minimum valid value is 1 MiB. If you specify a value less
-  than 1 MiB, an error occurs. For more information about supported byte size
-  units, see
-  {ref}/common-options.html#byte-units[Byte size units].
+  created in versions earlier than 6.1 is `4096mb`.
++
+--
+If you specify a number instead of a string, the units are assumed to be MiB.
+Specifying a string is recommended for clarity. If you specify a byte size unit
+of `b` or `kb` and the number does not equate to a discrete number of megabytes,
+it is rounded down to the closest MiB. The minimum valid value is 1 MiB. If you
+specify a value less than 1 MiB, an error occurs. For more information about
+supported byte size units, see
+{ref}/common-options.html#byte-units[Byte size units].
+
+If your `elasticsearch.yml` file contains an `xpack.ml.max_model_memory_limit`
+setting, an error occurs when you try to create jobs that have
+`model_memory_limit` values greater than that setting. For more information,
+see <<ml-settings>>.
+--
 
 [float]
 [[ml-apimodelplotconfig]]

docs/en/settings/ml-settings.asciidoc

@@ -11,6 +11,17 @@ You do not need to configure any settings to use {ml}. It is enabled by default.
 [[general-ml-settings]]
 ==== General Machine Learning Settings
 
+`node.ml`::
+Set to `true` (default) to identify the node as a _machine learning node_. +
++
+If set to `false` in `elasticsearch.yml`, the node cannot run jobs. If set to
+`true` but `xpack.ml.enabled` is set to `false`, the `node.ml` setting is
+ignored and the node cannot run jobs. If you want to run jobs, there must be at
+least one machine learning node in your cluster. +
++
+IMPORTANT: On dedicated coordinating nodes or dedicated master nodes, disable
+the `node.ml` role.
+
 `xpack.ml.enabled`::
 Set to `true` (default) to enable {ml} on the node. +
 +
@@ -26,16 +37,12 @@ IMPORTANT: If you want to use {ml} features in your cluster, you must have
 `xpack.ml.enabled` set to `true` on all master-eligible nodes. This is the
 default behavior.
 
-`node.ml`::
-Set to `true` (default) to identify the node as a _machine learning node_. +
-+
-If set to `false` in `elasticsearch.yml`, the node cannot run jobs. If set to
-`true` but `xpack.ml.enabled` is set to `false`, the `node.ml` setting is
-ignored and the node cannot run jobs. If you want to run jobs, there must be at
-least one machine learning node in your cluster. +
-+
-IMPORTANT: On dedicated coordinating nodes or dedicated master nodes, disable
-the `node.ml` role.
-
 `xpack.ml.max_open_jobs`::
 The maximum number of jobs that can run on a node. Defaults to `10`.
+
+`xpack.ml.max_model_memory_limit`::
+The maximum `model_memory_limit` property value that can be set for any job on
+this node. If you try to create a job with a `model_memory_limit` property value
+that is greater than this setting value, an error occurs. Existing jobs are not
+affected when you update this setting. For more information about the
+`model_memory_limit` property, see <<ml-apilimits>>.