Add beta threat intel sources to beta threat intel article (#4895)

Author: jpipkin1

docs/platform-services/threat-intelligence-indicators.md

@@ -39,7 +39,11 @@ You do not need to be assigned these role capabilities to [find threats with log
 
 To search logs that contain correlations to threat intelligence indicators, you must first ingest the indicators. You can ingest indicators using:
 * **The Threat Intelligence tab**. See [Add indicators in the Threat Intelligence tab](#add-indicators-in-the-threat-intelligence-tab).
-* **A collector**. See [STIX/TAXII 2 Client Source](/docs/send-data/hosted-collectors/cloud-to-cloud-integration-framework/stix-taxii-2-client-source) and [STIX/TAXII 1 Client Source](/docs/send-data/hosted-collectors/cloud-to-cloud-integration-framework/stix-taxii-1-client-source).
+* **A collector**. See:
+   * [Intel471 Threat Intel Source](/docs/send-data/hosted-collectors/cloud-to-cloud-integration-framework/intel471-threat-intel-source)
+   * [Mandiant Threat Intel Source](/docs/send-data/hosted-collectors/cloud-to-cloud-integration-framework/mandiant-threat-intel-source)
+   * [STIX/TAXII 1 Client Source](/docs/send-data/hosted-collectors/cloud-to-cloud-integration-framework/stix-taxii-1-client-source)  
+   * [STIX/TAXII 2 Client Source](/docs/send-data/hosted-collectors/cloud-to-cloud-integration-framework/stix-taxii-2-client-source)
 * **The API**. See the following APIs in the [Threat Intel Ingest Management](https://api.sumologic.com/docs/#tag/threatIntelIngest) API resource:
    * [uploadNormalizedIndicators API](https://api.sumologic.com/docs/#operation/uploadNormalizedIndicators)
    * [uploadCsvIndicators API](https://api.sumologic.com/docs/#operation/uploadCsvIndicators)