(DOCSP-30680, DOCSP-31329, & DOCSP-31330): Add Property-Lvl Encryptio…

…n, User Presence, and Client Reset to Kotlin example cards (mongodb#2935)

## Pull Request Info

Add example project cards for: 
- [Property-Level
Encryption](https://github.com/realm/realm-kotlin-samples/blob/main/AppServicesUsageSamples/apps/property-encryption/README.md)
- [Client Reset and Error
Handling](https://github.com/realm/realm-kotlin-samples/blob/main/AppServicesUsageSamples/apps/error-handling/README.md)
- [Presence
Detection](https://github.com/realm/realm-kotlin-samples/blob/main/AppServicesUsageSamples/apps/presence-detection/README.md)

### Jira

- https://jira.mongodb.org/browse/DOCSP-30680
- https://jira.mongodb.org/browse/DOCSP-31329
- https://jira.mongodb.org/browse/DOCSP-31330

### Staged Changes

- [Kotlin SDK landing
page](https://docs-mongodbcom-staging.corp.mongodb.com/realm/docsworker-xlarge/docsp-31329-31330-sample-apps/sdk/kotlin/#example-projects)

### Reminder Checklist

If your PR modifies the docs, you might need to also update some
corresponding
pages. Check if completed or N/A.

- [x] Create Jira ticket for corresponding docs-app-services update(s),
if any
- [x] Checked/updated Admin API
- [x] Checked/updated CLI reference

### Review Guidelines


[REVIEWING.md](https://github.com/mongodb/docs-realm/blob/master/REVIEWING.md)

source/sdk/kotlin.txt

@@ -186,3 +186,42 @@ Recommended Reading
       :icon-alt: Migrate Icon
 
       Learn why and how to switch from the Java SDK to the Kotlin SDK.
+
+Example Projects
+----------------
+
+Explore engineering and community-provided example projects to learn best 
+practices and common development patterns for Realm and Atlas App Services
+using the Kotlin SDK.
+
+.. card-group::
+   :columns: 3
+   :style: extra-compact
+
+   .. card::
+      :headline: Property-Level Encryption
+      :cta: Example project
+      :url: https://github.com/realm/realm-kotlin-samples/blob/main/AppServicesUsageSamples/apps/property-encryption/README.md
+      :icon: /images/icons/branding_2023/General_SECURITY_Encryption10x.png
+      :icon-alt: Encryption Icon
+
+      Enhance user data security with property-level encryption.
+
+   .. card::
+      :headline: User's Online State
+      :cta: Example project
+      :url: https://github.com/realm/realm-kotlin-samples/blob/main/AppServicesUsageSamples/apps/presence-detection/README.md
+      :icon: /images/icons/branding_2023/Technical_REALM_Offline10x.png
+      :icon-alt: Realm Offline Icon
+
+      Detect connectivity and activity of users and devices. 
+
+   .. card::
+      :headline: Connection State Change & Error Handling
+      :cta: Example project
+      :url: https://github.com/realm/realm-kotlin-samples/blob/main/AppServicesUsageSamples/apps/error-handling/README.md
+      :icon: /images/icons/branding_2023/General_CLOUD_Mobility10x.png
+      :icon-alt: Cloud Mobile Transfer Icon
+
+      Learn best practices around handling Sync errors and client reset 
+      strategies.