remove some 'a' methods

apps/docs/docs/modules/low_level/response_synthesizer.md

@@ -40,7 +40,7 @@ const nodesWithScore: NodeWithScore[] = [
   },
 ];
 
-const response = await responseSynthesizer.asynthesize(
+const response = await responseSynthesizer.synthesize(
   "What age am I?",
   nodesWithScore
 );

apps/docs/docs/modules/low_level/retriever.md

@@ -11,7 +11,7 @@ const retriever = vector_index.asRetriever()
 retriever.similarityTopK = 3;
 
 // Fetch nodes!
-const nodesWithScore = await retriever.aretrieve("query string");
+const nodesWithScore = await retriever.retrieve("query string");
 ```
 
 ## API Reference