[9.0] [DOCS] Add minimal synthetic APIs (#214518) (#217900)

# Backport

This will backport the following commits from `main` to `9.0`:
- [[DOCS] Add minimal synthetic APIs
(#214518)](https://github.com/elastic/kibana/pull/214518)

<!--- Backport version: 9.6.6 -->

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

<!--BACKPORT [{"author":{"name":"Lisa
Cawley","email":"lcawley@elastic.co"},"sourceCommit":{"committedDate":"2025-04-10T17:26:49Z","message":"[DOCS]
Add minimal synthetic APIs (#214518)\n\nCo-authored-by: Colleen McGinnis
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Add minimal synthetic
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Add minimal synthetic APIs (#214518)\n\nCo-authored-by: Colleen McGinnis
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Add minimal synthetic APIs (#214518)\n\nCo-authored-by: Colleen McGinnis
<colleen.j.mcginnis@gmail.com>","sha":"e00f013b62a42a2870be3b7a3e4cadab8ba191c4"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"8.18","label":"v8.18.1","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"9.0","label":"v9.0.1","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

oas_docs/overlays/kibana.overlays.yaml

@@ -80,6 +80,28 @@ actions:
     description: Change displayName
     update:
       x-displayName: "User session management"
+  - target: '$.tags[?(@.name=="saved objects")]'
+    description: Change displayName and description
+    update:
+      x-displayName: "Saved objects"
+      description: |
+        Export sets of saved objects that you want to import into Kibana, resolve import errors, and rotate an encryption key for encrypted saved objects with the saved objects APIs.
+
+        To manage a specific type of saved object, use the corresponding APIs.
+        For example, use:
+
+        * [Data views](../group/endpoint-data-views)
+        * [Spaces](https://www.elastic.co/guide/en/kibana/current/spaces-api.html)
+        * [Short URLs](https://www.elastic.co/guide/en/kibana/current/short-urls-api.html)
+
+        Warning: Do not write documents directly to the `.kibana` index. When you write directly to the `.kibana` index, the data becomes corrupted and permanently breaks future Kibana versions
+  - target: '$.tags[?(@.name=="synthetics")]'
+    description: Add tag info
+    update:
+        x-displayName: Synthetics
+        externalDocs:
+          description: Synthetic monitoring
+          url: https://www.elastic.co/guide/en/observability/current/monitor-uptime-synthetics.html
 # Remove extra tags from operations
   - target: "$.paths[*][*].tags[1:]"
     description: Remove all but first tag from operations

oas_docs/scripts/merge_ess_oas.js

@@ -31,6 +31,7 @@ const { REPO_ROOT } = require('@kbn/repo-info');
       `${REPO_ROOT}/x-pack/solutions/observability/plugins/apm/docs/openapi/apm/bundled.yaml`,
       `${REPO_ROOT}/x-pack/solutions/observability/plugins/slo/docs/openapi/slo/bundled.yaml`,
       `${REPO_ROOT}/x-pack/solutions/observability/plugins/uptime/docs/openapi/uptime_apis.yaml`,
+      `${REPO_ROOT}/x-pack/solutions/observability/plugins/synthetics/docs/openapi/synthetic_apis.yaml`,
 
       // Security solution
       `${REPO_ROOT}/x-pack/solutions/security/plugins/security_solution/docs/openapi/ess/*.schema.yaml`,

x-pack/solutions/observability/plugins/synthetics/docs/openapi/README.md

@@ -0,0 +1,8 @@
+# OpenAPI (Experimental)
+
+The current self-contained spec file is YAML and can be used for online tools like those found at <https://openapi.tools/>.
+This spec is experimental and may be incomplete or change later.
+
+A guide about the OpenApi specification can be found at [https://swagger.io/docs/specification/about/](https://swagger.io/docs/specification/about/).
+
+To join these files with the rest of the Kibana APIs, refer to `oas_docs/README.md`