[Documentation] source overview

Author: badmonster0

docs/docs/sources/index.md

@@ -6,6 +6,23 @@ description: CocoIndex Built-in Sources
 
 # CocoIndex Built-in Sources
 
+In CocoIndex, a source is the data origin you import from (e.g., files, databases, APIs) that feeds into an indexing flow for transformation and retrieval.
+
+| Source Type    | See Also                    |
+|------------------|-------------------------|
+| LocalFile | Local File System   |
+| AmazonS3 | Amazon S3   |
+| AzureBlob | Azure Blob Storage   |
+| GoogleDrive | Google Drive   |
+| Postgres | PostgreSQL   |
+
+Related:
+- [Life cycle of a indexing flow](/docs/core/basics#life-cycle-of-an-indexing-flow) 
+- [Live Update Tutorial](/docs/tutorials/live_updates) 
+for change capture mechanisms.
+
+
+
 ## LocalFile
 
 The `LocalFile` source imports files from a local file system.

docs/docs/targets/index.md

@@ -20,6 +20,8 @@ The way to map data from a data collector to a target depends on data model of t
 | [Neo4j](/docs/targets/neo4j)       | [Property graph](#property-graph-targets)        |
 | [Kuzu](/docs/targets/kuzu)         | [Property graph](#property-graph-targets)        |
 
+If you are looking for targets beyond here, you can always use [custom targets](/docs/custom_ops/custom_targets) as building blocks.
+
 
 ## Property Graph Targets
 Property graph is a widely-adopted model for knowledge graphs, where both nodes and relationships can have properties.