docs: update OSA knowledge sync documentation

- Add hed-python to list of synced GitHub repositories
- Document automatic paper deduplication feature

Author: neuromechanist

docs/osa/knowledge-sync.md

@@ -62,6 +62,7 @@ Options:
 - `hed-standard/hed-specification`
 - `hed-standard/hed-schemas`
 - `hed-standard/hed-javascript`
+- `hed-standard/hed-python`
 
 ### `osa sync papers`
 
@@ -85,6 +86,9 @@ Options:
 - `-s, --source`: Paper source (`openalex`, `semanticscholar`, `pubmed`)
 - `-q, --query`: Custom search query (default: "HED annotation" OR "Hierarchical Event Descriptors")
 
+!!! info "Automatic Deduplication"
+    Papers are automatically deduplicated using fuzzy title matching. The same paper from different sources (e.g., OpenALEX and Semantic Scholar) is only shown once in search results.
+
 ### `osa sync all`
 
 Sync all knowledge sources (GitHub + papers).