adding error message info (#702)

* adding error message info

* Update website/pages/en/querying/querying-the-graph.mdx

Author: idalithb

website/pages/en/querying/querying-the-graph.mdx

@@ -6,6 +6,8 @@ When a subgraph is published to The Graph Network, you can visit its subgraph de
 
 > Please see the [Query API](/querying/graphql-api) for a complete reference on how to query the subgraph's entities. You can learn about GraphQL querying best practices [here](/querying/querying-best-practices)
 
+> Note: If you encounter 405 errors with a GET request to the Graph Explorer URL, please switch to a POST request instead.
+
 Each subgraph published to The Graph Network has a unique query URL in Graph Explorer for making direct queries that you can find by navigating to the subgraph details page and clicking on the "Query" button on the top right corner.
 
 ![Query Subgraph Pane](/img/query-subgraph-pane.png)