Add links to Serverless web estimator (#3871)

Apologies for interrupting On Week. These came up during today's issues
triage.

This adds a link to the new "Serverless estimator" on the Security
billing dimensions and the Observability billing dimensions pages.

Closes: elastic/docs-content-internal#495
Closes: elastic/docs-content-internal#496

---

[Observability
update](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/3871/deploy-manage/cloud-organization/billing/elastic-observability-billing-dimensions):

<img width="567" height="90" alt="obs"
src="https://github.com/user-attachments/assets/4559fd03-1d2d-4cd9-893a-29d23d50efa8"
/>

---

[Security
update](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/3871/deploy-manage/cloud-organization/billing/security-billing-dimensions):

<img width="574" height="192" alt="sec"
src="https://github.com/user-attachments/assets/d0289bf0-8c76-4d5d-a44e-4c61f3c8e417"
/>

Author: kilfoyle

deploy-manage/cloud-organization/billing/elastic-observability-billing-dimensions.md

@@ -22,7 +22,7 @@ Your monthly bill is based on the capabilities you use. When you use {{obs-serve
 
 Data volumes for ingest and retention are based on the fully enriched normalized data size at the end of the ingest pipeline, before {{es}} compression is performed, and will be higher than the volumes traditionally reported by {{es}} index size. In addition, these volumes might be larger than those reported by cloud provider proxy logs for data going into {{es}}. This allows you to have flexibility in choosing your preferred ingest architecture for enrichment, whether it’s through Elastic Agent, Logstash, OpenTelemetry, or collectors — with no impact on the cost.
 
-Refer to [Serverless billing dimensions](serverless-project-billing-dimensions.md) and the [{{ecloud}} pricing table](https://cloud.elastic.co/cloud-pricing-table?productType=serverless&project=observability) for more details about {{obs-serverless}} billing dimensions and rates.
+Refer to [Serverless billing dimensions](serverless-project-billing-dimensions.md) and the [{{ecloud}} pricing table](https://cloud.elastic.co/cloud-pricing-table?productType=serverless&project=observability) for more details about {{obs-serverless}} billing dimensions and rates, or you can create a [Serverless estimate](https://cloud.elastic.co/pricing/serverless?s=observability).
 
 ## Synthetics [synthetics-billing]
 

deploy-manage/cloud-organization/billing/security-billing-dimensions.md

@@ -22,6 +22,7 @@ Your monthly bill is based on the capabilities you use. When you use Security An
 
 Data volumes for ingest and retention are based on the fully enriched normalized data size at the end of the ingest pipeline, before {{es}} compression is performed, and will be higher than the volumes traditionally reported by {{es}} index size. In addition, these volumes might be larger than those reported by cloud provider proxy logs for data going into {{es}}. This allows you to have flexibility in choosing your preferred ingest architecture for enrichment, whether it’s through {{agent}}, {{ls}}, OpenTelemetry, or collectors — with no impact on the cost.
 
+[Create a serverless estimate](https://cloud.elastic.co/pricing/serverless?s=security) or refer to the [{{ecloud}} pricing table](https://cloud.elastic.co/cloud-pricing-table?productType=serverless&project=security) for more details.
 
 ## Endpoint Protection [security-billing-endpoint-protection]