chore(docs): add graphql example

docs/docs/usage/graphql.md

@@ -0,0 +1,49 @@
+# GraphQL
+
+Create a file with the `.http` extension and write your GraphQL requests in it.
+
+## With variables
+
+```http title="gql-with-variables.http"
+
+# @graphql 1
+POST https://swapi-graphql.netlify.app/.netlify/functions/index HTTP/1.1
+accept: application/json
+
+query Person($id: ID) {
+  person(personID: $id) {
+    name
+  }
+}
+variables { "id": 1 }
+
+```
+
+## Without variables
+
+```http title="gql-without-variables.http"
+
+# @graphql 1
+POST https://swapi-graphql.netlify.app/.netlify/functions/index HTTP/1.1
+accept: application/json
+
+query Query {
+  allFilms {
+    films {
+      title
+      director
+      releaseDate
+      speciesConnection {
+        species {
+          name
+          classification
+          homeworld {
+            name
+          }
+        }
+      }
+    }
+  }
+}
+
+```