Clarify how user search works

This adds a few points which should shed light on how to search users
using a drop-down list in Rancher, whether to add users to clusters or
to projects.

docs/how-to-guides/new-user-guides/add-users-to-projects.md

@@ -29,7 +29,10 @@ Following project creation, you can add users as project members so that they ca
 1. Click **Cluster > Projects/Namespaces**.
 1. Go to the project where you want to add members. Next to the **Create Namespace** button above the project name, click **☰**. Select **Edit Config**.
 1. In the **Members** tab, click **Add**.
-1. Search for the user or group that you want to add to the project.
+1. Search for the user or group that you want to add to the project. Note that:
+  * At least 2 characters must be typed in the search box for results to appear
+  * Users can be searched based on their username or display name
+  * Search is case-sensitive
 
     If external authentication is configured:
 
@@ -63,4 +66,4 @@ Following project creation, you can add users as project members so that they ca
 **Result:** The chosen users are added to the project.
 
 - To revoke project membership, select the user and click **Delete**. This action deletes membership, not the user.
-- To modify a user's roles in the project, delete them from the project, and then re-add them with modified roles.
+- To modify a user's roles in the project, delete them from the project, and then re-add them with modified roles.

docs/how-to-guides/new-user-guides/manage-clusters/access-clusters/add-users-to-clusters.md

@@ -31,7 +31,10 @@ Cluster administrators can edit the membership for a cluster, controlling which
 1. Click **☰ > Cluster Management**.
 1. Go to the cluster you want to add members to and click **⋮ > Edit Config**.
 1. In the **Member Roles** tab, click **Add Member**.
-1. Search for the user or group that you want to add to the cluster.
+1. Search for the user or group that you want to add to the cluster. Note that:
+  * At least 2 characters must be typed in the search box for results to appear
+  * Users can be searched based on their username or display name
+  * Search is case-sensitive
 
     If external authentication is configured:
 

docs/how-to-guides/new-user-guides/manage-clusters/projects-and-namespaces.md

@@ -168,7 +168,11 @@ By default, your user is added as the project `Owner`.
 To add members:
 
 1. In the **Members** tab, click **Add**.
-1. From the **Select Member** field, search for a user or group that you want to assign project access. Note: You can only search for groups if external authentication is enabled.
+1. From the **Select Member** field, search for a user or group that you want to assign project access. Keep in mind that:
+  * You can only search for groups if external authentication is enabled
+  * At least 2 characters must be typed in the search box for results to appear
+  * Users can be searched based on their username or display name
+  * Search is case-sensitive
 1. In the **Project Permissions** section, choose a role. For more information, refer to the [documentation on project roles.](../authentication-permissions-and-global-configuration/manage-role-based-access-control-rbac/cluster-and-project-roles.md)
 
 ### 4. Optional: Add Resource Quotas