[DOCS] Adds deleting flag to the GET job stats API docs (#53223)

docs/reference/ml/anomaly-detection/apis/get-job-stats.asciidoc

@@ -135,6 +135,11 @@ include::{docdir}/ml/ml-shared.asciidoc[tag=processed-record-count]
 (long)
 include::{docdir}/ml/ml-shared.asciidoc[tag=sparse-bucket-count]
 
+`deleting`::
+(boolean)
+Indicates that the process of deleting the job is in progress but not yet 
+completed. It is only reported when `true`.
+
 [[forecastsstats]]`forecasts_stats`::
 (object) An object that provides statistical information about forecasts 
 belonging to this job. Some statistics are omitted if no forecasts have been