[DOCS] Update model_memory_limit (elastic/x-pack-elasticsearch#1928)

* [DOCS] Update model_memory_limit

* [DOCS] Clarify minimum model_memory_limit value

* [DOCS] More updates to model_memory_limit

* [DOCS] Address feedback in jobresource.asciidoc

Original commit: elastic/x-pack-elasticsearch@3c62719037

docs/en/ml/getting-started.asciidoc

@@ -483,12 +483,13 @@ The number of records that have been processed by the job.
 Memory status::
 The status of the mathematical models. When you create jobs by using the APIs or
 by using the advanced options in {kib}, you can specify a `model_memory_limit`.
-That value is the maximum amount of memory resources, in MiB, that the
+That value is the maximum amount of memory resources that the mathematical
-mathematical models can use. Once that limit is approached, data pruning becomes
+models can use. Once that limit is approached, data pruning becomes more
-more aggressive. Upon exceeding that limit, new entities are not modeled.
+aggressive. Upon exceeding that limit, new entities are not modeled. For more
-The default value is `4096`. The memory status field reflects whether you have
+information about this setting, see
-reached or exceeded the model memory limit. It can have one of the following
+{ref}/ml-job-resource.html#ml-apilimits[Analysis Limits]. The memory status
-values: +
+field reflects whether you have reached or exceeded the model memory limit. It
+can have one of the following values: +
 `ok`::: The models stayed below the configured value.
 `soft_limit`::: The models used more than 60% of the configured memory limit
 and older unused models will be pruned to free up space.

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

@@ -277,10 +277,17 @@ For more information, see
 //<<ml-configuring-categories>>.
 
 `model_memory_limit`::
-  (long) The approximate maximum amount of memory resources that are required
+  (long or string) The approximate maximum amount of memory resources that are
-  for analytical processing, in MiB. Once this limit is approached, data pruning
+  required for analytical processing. Once this limit is approached, data pruning
   becomes more aggressive. Upon exceeding this limit, new entities are not
-  modeled. The default value is 4096.
+  modeled. The default value 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].
 
 [float]
 [[ml-apimodelplotconfig]]

docs/en/rest-api/ml/update-job.asciidoc

@@ -23,8 +23,7 @@ The following properties can be updated after the job is created:
 |Name |Description |Requires Restart
 
 |`analysis_limits`: `model_memory_limit` |The approximate maximum amount of
-memory resources required for analytical processing, in MiB.
+memory resources required for analytical processing. See <<ml-apilimits>>. | Yes
-See <<ml-apilimits>>. | Yes
 
 |`background_persist_interval` |Advanced configuration option. The time between
 each periodic persistence of the model. See <<ml-job-resource>>. | Yes