[Reference] Revisit the data analysis landing page (#1355)

This PR updates the data analysis landing page.
Relates to #1303

---------

Co-authored-by: Lisa Cawley <[email protected]>

Author: alaudazzi

reference/data-analysis/index.md

@@ -1,10 +1,12 @@
 # Data analysis
 
-% TO-DO: Add links to "What is data analysis?"%
-
 This section contains reference information for data analysis features, including:
 
+* [Supplied {{anomaly-detect}} configurations](/reference/data-analysis/machine-learning/supplied-anomaly-detection-configurations.md)
+* [Function reference for anomaly detection jobs](/reference/data-analysis/machine-learning/machine-learning-functions.md)
+* [Metrics reference for the Infrastructure app](/reference/data-analysis/observability/index.md)
+* [Canvas functions](/reference/data-analysis/kibana/canvas-functions.md)
 * [Text analysis components](elasticsearch://reference/text-analysis/index.md)
 * [Aggregations](elasticsearch://reference/aggregations/index.md)
-* [Machine learning functions](/reference/data-analysis/machine-learning/machine-learning-functions.md)
-* [Canvas functions](/reference/data-analysis/kibana/canvas-functions.md)
+
+Visit the [Explore and analyze](/explore-analyze/index.md) section to learn how to use the Elasticsearch platform to explore and analyze your data effectively.