Merge branch 'docs-add-25k-hybrid' into 'master'

Add Cloud Native Hybrid instructions on 25k users RA page

See merge request gitlab-org/gitlab!65154

doc/administration/reference_architectures/index.md

@@ -72,6 +72,7 @@ The following reference architectures are available:
 The following Cloud Native Hybrid reference architectures, where select recommended components can be run in Kubernetes, are available:
 
 - [Up to 10,000 users](10k_users.md#cloud-native-hybrid-reference-architecture-with-helm-charts-alternative)
+- [Up to 25,000 users](25k_users.md#cloud-native-hybrid-reference-architecture-with-helm-charts-alternative)
 - [Up to 50,000 users](50k_users.md#cloud-native-hybrid-reference-architecture-with-helm-charts-alternative)
 
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