[9.2] [DOCS] Add synthetic API response descriptions (#240917) (#241202)

# Backport

This will backport the following commits from `main` to `9.2`:
- [[DOCS] Add synthetic API response descriptions
(#240917)](#240917)

<!--- Backport version: 10.1.0 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Lisa
Cawley","email":"[email protected]"},"sourceCommit":{"committedDate":"2025-10-28T20:32:05Z","message":"[DOCS]
Add synthetic API response descriptions
(#240917)","sha":"38ada44bb2dddca770b89a7bb726b1696803154a","branchLabelMapping":{"^v9.3.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["Team:Docs","release_note:skip","Team:Fleet","docs","Team:obs-ux-management","backport:version","v9.3.0","v9.2.1"],"title":"[DOCS]
Add synthetic API response
descriptions","number":240917,"url":"https://github.com/elastic/kibana/pull/240917","mergeCommit":{"message":"[DOCS]
Add synthetic API response descriptions
(#240917)","sha":"38ada44bb2dddca770b89a7bb726b1696803154a"}},"sourceBranch":"main","suggestedTargetBranches":["9.2"],"targetPullRequestStates":[{"branch":"main","label":"v9.3.0","branchLabelMappingKey":"^v9.3.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/240917","number":240917,"mergeCommit":{"message":"[DOCS]
Add synthetic API response descriptions
(#240917)","sha":"38ada44bb2dddca770b89a7bb726b1696803154a"}},{"branch":"9.2","label":"v9.2.1","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

---------

Co-authored-by: kibanamachine <[email protected]>

Author: lcawl

oas_docs/output/kibana.yaml

@@ -70453,6 +70453,7 @@ paths:
                       description: The unique identifier of the deleted monitor.
                       type: string
                 type: array
+          description: A successful response.
       summary: Delete monitors
       tags:
         - synthetics
@@ -70558,6 +70559,7 @@ paths:
                     }
               schema:
                 type: object
+          description: A successful response.
         '404':
           description: If the monitor is not found, the API returns a 404 error.
       summary: Get a monitor

src/platform/packages/private/kbn-validate-oas/oas_error_baseline.json

@@ -1,4 +1,4 @@
 {
-  "./oas_docs/output/kibana.yaml": 75,
+  "./oas_docs/output/kibana.yaml": 73,
   "./oas_docs/output/kibana.serverless.yaml": 276
 }

x-pack/solutions/observability/plugins/synthetics/docs/openapi/synthetic_apis.yaml

@@ -295,6 +295,7 @@ paths:
             type: string
       responses:
         '200':
+          description: A successful response.
           content:
             application/json:
               schema:
@@ -475,6 +476,7 @@ paths:
                   }
       responses:
         '200':
+          description: A successful response.
           content:
             application/json:
               schema: