docs: add openshift replicasets examples (#209)

Signed-off-by: Rui-Dias-Gomes <rui.dias.gomes@ibm.com>
Co-authored-by: Rui-Dias-Gomes <rui.dias.gomes@ibm.com>

docs/deployment.md

@@ -192,3 +192,45 @@ curl -X 'POST' \
     "http_sources": [{"url": "https://arxiv.org/pdf/2501.17887"}]
   }'
 ```
+
+### ReplicaSets with `sticky sessions`
+
+Manifest example: [docling-serve-replicas-w-sticky-sessions.yaml](./deploy-examples/docling-serve-replicas-w-sticky-sessions.yaml)
+
+This deployment has the following features:
+
+- Deployment configuration with 3 replicas
+- Service configuration
+- Expose the service using a OpenShift `Route` and enables sticky sessions
+
+Install the app with:
+
+```sh
+oc apply -f docs/deploy-examples/docling-serve-replicas-w-sticky-sessions.yaml
+```
+
+For using the API:
+
+```sh
+# Retrieve the endpoint
+DOCLING_NAME=docling-serve
+DOCLING_ROUTE="https://$(oc get routes $DOCLING_NAME --template={{.spec.host}})"
+
+# Make a test query, store the cookie and taskid
+task_id=$(curl -s -X 'POST' \
+    "${DOCLING_ROUTE}/v1alpha/convert/source/async" \
+    -H "accept: application/json" \
+    -H "Content-Type: application/json" \
+    -d '{
+    "http_sources": [{"url": "https://arxiv.org/pdf/2501.17887"}]
+    }' \
+    -c cookies.txt | grep -oP '"task_id":"\K[^"]+')
+```
+
+```sh
+# Grab the taskid and cookie to check the task status
+curl -v -X 'GET' \
+  "${DOCLING_ROUTE}/v1alpha/status/poll/$task_id?wait=0" \
+  -H "accept: application/json" \
+  -b "cookies.txt"
+```