Add docs about Issue #5241 (#5309)

* docs(install-guide): update Go 1.24 tool directive usage

The previous installation guide relied on tools.go for tracking dependencies.
This update replaces it with the new tool directive introduced in Go 1.24.

Fixes #5254

* docs:add docs about "ref to reference unused messages for openapi.json inclusion"

Fixes #5241

* fix: update docs about using ref to reference unused messages

* fix: modify the document name and document location.

* fix: update docs suffix

docs/docs/mapping/using_ref_with_responses.md

@@ -0,0 +1,57 @@
+# Using arbitrary messages in response description
+
+Assuming a protobuf file of the structure
+
+```protobuf
+syntax = "proto3";
+
+package example.service.v1;
+
+import "protoc-gen-openapiv2/options/annotations.proto";
+
+service GenericService {
+  rpc GenericRPC(GenericRPCRequest) returns (GenericRPCResponse);
+}
+
+message GenericRPCRequest {
+  string id = 1;
+}
+
+message GenericRPCResponse {
+  string result = 1;
+}
+```
+
+If you want your OpenAPI document to include a custom response for all RPCs defined in this protobuf file, you can add the following:
+
+```protobuf
+option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_swagger) = {
+  responses: {
+    key: "400"
+    value: {
+      description: "Returned when the request is malformed."
+      schema: {
+        json_schema: {ref: ".example.service.v1.GenericResponse"} // Must match the fully qualified name of the message
+      }
+    }
+  }
+};
+
+message GenericResponse {
+  repeated string resources = 1;
+  repeated string errors = 2;
+}
+```
+
+When generating, you will see the following response included in your OpenAPI document:
+
+```json
+"400": {
+  "description": "Returned when the request is malformed.",
+  "schema": {
+    "$ref": "#/definitions/v1GenericResponse"
+  }
+},
+```
+
+The annotation can also be specified per-rpc.