Add links

Author: lcawl

docs/cli/release/changelog-add.md

@@ -40,15 +40,19 @@ docs-builder changelog add [options...] [-h|--help]
 
 `--products <List<ProductInfo>>`
 :   Required: Products affected in format "product target lifecycle, ..." (for example, `"elasticsearch 9.2.0 ga, cloud-serverless 2025-08-05"`).
+:   The valid product identifiers are listed in [products.yml](https://github.com/elastic/docs-builder/blob/main/config/products.yml).
+:   The valid lifecycles are listed in [ChangelogConfiguration.cs](https://github.com/elastic/docs-builder/blob/main/src/services/Elastic.Documentation.Services/Changelog/ChangelogConfiguration.cs).
 
 `--pr <string?>`
 :   Optional: Pull request number.
 
 `--subtype <string?>`
 :   Optional: Subtype for breaking changes (for example, `api`, `behavioral`, or `configuration`).
+:   The valid subtypes are listed in [ChangelogConfiguration.cs](https://github.com/elastic/docs-builder/blob/main/src/services/Elastic.Documentation.Services/Changelog/ChangelogConfiguration.cs).
 
 `--title <string>`
 :    Required: A short, user-facing title (max 80 characters)
 
 `--type <string>`
-:   Required: Type of change (for example, `feature`, `enhancement`, `bug-fix`, or `breaking-change`)
+:   Required: Type of change (for example, `feature`, `enhancement`, `bug-fix`, or `breaking-change`).
+:   The valid types are listed in [ChangelogConfiguration.cs](https://github.com/elastic/docs-builder/blob/main/src/services/Elastic.Documentation.Services/Changelog/ChangelogConfiguration.cs).