fix typo

docs/api/remove.md

@@ -369,7 +369,7 @@ gRPC has a message size limitation.<br>
 Please be careful that the size of the request exceeds the limit.
 </div>
 
-## Input
+### Input
 
 - the scheme of `payload.v1.Remove.MultiRequest`
 

docs/api/search.md

@@ -700,7 +700,7 @@ Here are some common reasons and how to resolve each error.
 | NOT_FOUND         | Search result is empty or insufficient to request result length.                                                | Send a request with another vector or set min_num to a smaller value.                    |
 | INTERNAL          | Target Vald cluster or network route has some critical error.                                                   | Check target Vald cluster first and check network route including ingress as second.     |
 
-### MultiSearchByID RPC
+## MultiSearchByID RPC
 
 MultiSearchByID RPC is the method to search vectors with multiple IDs in **1** request.
 
@@ -1485,7 +1485,7 @@ Here are some common reasons and how to resolve each error.
 | NOT_FOUND         | Search result is empty or insufficient to request result length.                                                | Send a request with another vector or set min_num to a smaller value.                    |
 | INTERNAL          | Target Vald cluster or network route has some critical error.                                                   | Check target Vald cluster first and check network route including ingress as second.     |
 
-### MultiLinearSearchByID RPC
+## MultiLinearSearchByID RPC
 
 MultiLinearSearchByID RPC is the method to linear search vectors with multiple IDs in **1** request.