[Docs] All Rollup docs experimental, agg limitations, clarify DeleteJob (#31299)

- All rollup pages should be marked as experimental instead of just
the top page
- While the job config docs state which aggregations are allowed, adding
a section which specifically details this in one place is more convenient
for the user
- Add a clarification that the DeleteJob API does not delete the rollup
data, just the rollup job.

Author: polyfractal

x-pack/docs/en/rest-api/rollup/delete-job.asciidoc

@@ -5,9 +5,37 @@
 <titleabbrev>Delete Job</titleabbrev>
 ++++
 
+experimental[]
+
 This API deletes an existing rollup job.  The job can be started or stopped, in both cases it will be deleted.  Attempting
 to delete a non-existing job will throw an exception
 
+.Deleting the job does not delete rolled up data
+**********************************
+When a job is deleted, that only removes the process that is actively monitoring and rolling up data.
+It does not delete any previously rolled up data.  This is by design; a user may wish to roll up a static dataset.  Because
+the dataset is static, once it has been fully rolled up there is no need to keep the indexing Rollup job around (as there
+will be no new data).  So the job may be deleted, leaving behind the rolled up data for analysis.
+
+If you wish to also remove the rollup data, and the rollup index only contains the data for a single job, you can simply
+delete the whole rollup index.  If the rollup index stores data from several jobs, you must issue a Delete-By-Query that
+targets the Rollup job's ID in the rollup index:
+
+
+[source,js]
+--------------------------------------------------
+POST my_rollup_index/_delete_by_query
+{
+  "query": {
+    "term": {
+      "_rollup.id": "the_rollup_job_id"
+    }
+  }
+}
+--------------------------------------------------
+// NOTCONSOLE
+
+**********************************
 ==== Request
 
 `DELETE _xpack/rollup/job/<job_id>`

x-pack/docs/en/rest-api/rollup/get-job.asciidoc

@@ -5,6 +5,8 @@
 <titleabbrev>Get Job</titleabbrev>
 ++++
 
+experimental[]
+
 This API returns the configuration, stats and status of rollup jobs.  The API can return the details for a single job,
 or for all jobs.
 

x-pack/docs/en/rest-api/rollup/put-job.asciidoc

@@ -5,6 +5,8 @@
 <titleabbrev>Create Job</titleabbrev>
 ++++
 
+experimental[]
+
 This API enables you to create a rollup job.  The job will be created in a `STOPPED` state, and must be
 started with the <<rollup-start-job,Start Job API>>.
 

x-pack/docs/en/rest-api/rollup/rollup-caps.asciidoc

@@ -5,6 +5,8 @@
 <titleabbrev>Get Rollup Caps</titleabbrev>
 ++++
 
+experimental[]
+
 This API returns the rollup capabilities that have been configured for an index or index pattern.  This API is useful
 because a rollup job is often configured to rollup only a subset of fields from the source index.  Furthermore, only
 certain aggregations can be configured for various fields, leading to a limited subset of functionality depending on

x-pack/docs/en/rest-api/rollup/rollup-job-config.asciidoc

@@ -2,6 +2,8 @@
 [[rollup-job-config]]
 === Rollup Job Configuration
 
+experimental[]
+
 The Rollup Job Configuration contains all the details about how the rollup job should run, when it indexes documents,
 and what future queries will be able to execute against the rollup index.
 

x-pack/docs/en/rest-api/rollup/rollup-search.asciidoc

@@ -5,6 +5,8 @@
 <titleabbrev>Rollup Search</titleabbrev>
 ++++
 
+experimental[]
+
 The Rollup Search endpoint allows searching rolled-up data using the standard query DSL.  The Rollup Search endpoint
 is needed because, internally, rolled-up documents utilize a different document structure than the original data.  The
 Rollup Search endpoint rewrites standard query DSL into a format that matches the rollup documents, then takes the response

x-pack/docs/en/rest-api/rollup/start-job.asciidoc

@@ -5,6 +5,8 @@
 <titleabbrev>Start Job</titleabbrev>
 ++++
 
+experimental[]
+
 This API starts an existing, stopped rollup job.  If the job does not exist an exception will be thrown.
 Starting an already started job has no action.
 

x-pack/docs/en/rest-api/rollup/stop-job.asciidoc

@@ -5,6 +5,8 @@
 <titleabbrev>Stop Job</titleabbrev>
 ++++
 
+experimental[]
+
 This API stops an existing, started rollup job.  If the job does not exist an exception will be thrown.
 Stopping an already stopped job has no action.
 

x-pack/docs/en/rollup/api-quickref.asciidoc

@@ -1,6 +1,8 @@
 [[rollup-api-quickref]]
 == API Quick Reference
 
+experimental[]
+
 Most {rollup} endpoints have the following base:
 
 [source,js]

x-pack/docs/en/rollup/index.asciidoc

@@ -18,7 +18,8 @@ for analysis, but at a fraction of the storage cost of raw data.
 * <<rollup-getting-started,Getting Started>>
 * <<rollup-api-quickref, API Quick Reference>>
 * <<rollup-understanding-groups,Understanding Rollup Grouping>>
-* <<rollup-search-limitations,Limitations of Rollup Search>>
+* <<rollup-agg-limitations,Rollup aggregation limitations>>
+* <<rollup-search-limitations,Rollup Search limitations>>
 
 
 --
@@ -27,4 +28,5 @@ include::overview.asciidoc[]
 include::api-quickref.asciidoc[]
 include::rollup-getting-started.asciidoc[]
 include::understanding-groups.asciidoc[]
+include::rollup-agg-limitations.asciidoc[]
 include::rollup-search-limitations.asciidoc[]