43984 setup experience psso UI updates (#45023)

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**Related issue:** Resolves #43984

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.

## Testing

- [x] QA'd all new/changed functionality manually


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Updated the setup experience "Users" card to explain automatic
creation of local accounts via identity provider credentials (PSSO),
improving clarity for admins.

* **Documentation**
* Added a learn-more link to PSSO local account documentation from the
Users card.

* **Style**
* Improved spacing and description layout within the Users card for
better readability.

[![Review Change
Stack](https://storage.googleapis.com/coderabbit_public_assets/review-stack-in-coderabbit-ui.svg)](https://app.coderabbit.ai/change-stack/fleetdm/fleet/pull/45023)
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changes/43984-setup-experience-users-ui-updates

@@ -0,0 +1 @@
+- Fleet UI: Updated setup experience Users card with link to PSSO local account documentation

frontend/pages/ManageControlsPage/SetupExperience/cards/Users/Users.tsx

@@ -155,7 +155,17 @@ const Users = ({ currentTeamId }: ISetupExperienceCardProps) => {
       />
       <PageDescription
         variant="right-panel"
-        content="Configure end user authentication and local account settings for hosts that automatically enroll to Fleet."
+        content={
+          <>
+            Customize local user accounts. You can automatically create local
+            user accounts using IdP credentials (PSSO).{" "}
+            <CustomLink
+              url={`${LEARN_MORE_ABOUT_BASE_LINK}/psso-local-account`}
+              text="Learn how"
+              newTab
+            />
+          </>
+        }
       />
       <SetupExperienceContentContainer>
         {renderContent()}

frontend/pages/ManageControlsPage/SetupExperience/cards/Users/_styles.scss

@@ -1,3 +1,9 @@
 .setup-experience-users {
   @include vertical-card-layout;
+
+  gap: $gap-page-component-inner;
+
+  &__section-description {
+    margin: 0;
+  }
 }