Update null value filtering approach

embeddings/README.md

@@ -5,7 +5,7 @@
 ## Taxonomic JSON Construction
 
 The `JSON` was created from the [TreeOfLife-200M catalog](../catalog.parquet) through the following process:
-* **Null Value Filtering:** Remove records where `kingdom`, `phylum`, `class`, `order`, `family`, `genus`, or `species` are `null`.
+* **Null Value Filtering:** Remove records where `kingdom` or `species` are `null`.
 * **Deduplication:** Rows are deduplicated based on the combination of `kingdom`, `phylum`, `class`, `order`, `family`, `genus`, and `species`. This ensures that each unique taxonomic combination appears exactly once.
     * **Common Name Handling:** Currently, the source metadata often contains multiple common names for a single unique taxonomic combination. During processing, **the first common name encountered** for a given unique taxonomic combination is retained. We plan future improvements to establish a definitive 1-to-1 mapping or a more comprehensive common name strategy.