Mention 3K reference architecture in 1K and 2K

doc/administration/reference_architectures/1k_users.md

@@ -16,7 +16,8 @@ requirements, a single-node solution with
 many organizations .
 
 > - **Supported users (approximate):** 1,000
-> - **High Availability:** No
+> - **High Availability:** No. For a highly-available environment, you can
+>   follow the [3K reference architecture](3k_users.md).
 
 | Users        | Configuration           | GCP            | AWS             | Azure          |
 |--------------|-------------------------|----------------|-----------------|----------------|

doc/administration/reference_architectures/2k_users.md

@@ -12,7 +12,8 @@ For a full list of reference architectures, see
 [Available reference architectures](index.md#available-reference-architectures).
 
 > - **Supported users (approximate):** 2,000
-> - **High Availability:** No
+> - **High Availability:** No. For a highly-available environment, you can
+>   follow the [3K reference architecture](3k_users.md).
 > - **Test requests per second (RPS) rates:** API: 40 RPS, Web: 4 RPS, Git: 4 RPS
 
 | Service                                  | Nodes  | Configuration           | GCP            | AWS          | Azure   |

doc/administration/reference_architectures/3k_users.md

@@ -7,12 +7,8 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 # Reference architecture: up to 3,000 users **(PREMIUM ONLY)**
 
-This page describes GitLab reference architecture for up to 3,000 users. For a
-full list of reference architectures, see
-[Available reference architectures](index.md#available-reference-architectures).
-
-NOTE:
-This reference architecture is designed to help your organization achieve a
+This page describes GitLab reference architecture for up to 3,000 users.
+It is designed to help your organization achieve a
 highly-available GitLab deployment. If you do not have the expertise or need to
 maintain a highly-available environment, you can have a simpler and less
 costly-to-operate environment by using the
@@ -20,6 +16,9 @@ costly-to-operate environment by using the
 If you have fewer than 3,000 users and still want a highly-available GitLab deployment,
 you should still use this reference architecture but scale down the node sizes.
 
+For a full list of reference architectures, see
+[Available reference architectures](index.md#available-reference-architectures).
+
 > - **Supported users (approximate):** 3,000
 > - **High Availability:** Yes
 > - **Test requests per second (RPS) rates:** API: 60 RPS, Web: 6 RPS, Git: 6 RPS