docs: add MongoDB storage support and improve storage client comment

lightrag/api/README.md

@@ -183,6 +183,7 @@ OracleVectorDBStorag        Oracle
 ```
 JsonDocStatusStorage        JsonFile(default)
 PGDocStatusStorage          Postgres
+MongoDocStatusStorage       MongoDB
 ```
 
 #### How Select Storage Type

lightrag/lightrag.py

@@ -557,8 +557,8 @@ class LightRAG:
         return storage_class
 
     def set_storage_client(self, db_client):
-        # Inject db to storage implementation (only tested on Oracle Database
-        # Deprecated, seting correct value to *_storage creating LightRAG insteaded
+        # Deprecated, seting correct value to *_storage of LightRAG insteaded
+        # Inject db to storage implementation (only tested on Oracle Database)
         for storage in [
             self.vector_db_storage_cls,
             self.graph_storage_cls,