feat(graphql): Document useOperationNameForRootSpan (#12124)

* feat(graphql): Document `useOperationNameForRootSpan`

* Update docs/platforms/javascript/common/configuration/integrations/graphql.mdx

Co-authored-by: Alex Krawiec <alex.krawiec@sentry.io>

---------

Co-authored-by: Alex Krawiec <alex.krawiec@sentry.io>

Author: s1gr1d

docs/platforms/javascript/common/configuration/integrations/graphql.mdx

@@ -60,3 +60,15 @@ _Type: `boolean`_
 If spans for the execution of the default resolver on object properties should not be created. Default is `true`.
 
 When a resolver function is not defined on the schema for a field, GraphQL will use the default resolver which just looks for a property with that name on the object. If the property is not a function, it's not very interesting to trace. This option can reduce noise and number of spans created.
+
+### `useOperationNameForRootSpan`
+
+_Type: `boolean`_
+
+By default, this option is `true`.
+
+With this setting enabled, the GraphQL instrumentation dynamically updates the name of the `http.server` root span by appending
+the operation names. Instead of generic span names like `POST /graphql`, span names will be more descriptive, such as `POST /graphql (query MyQuery)`.
+For requests containing multiple operations, the span names will aggregate operation names, for example `POST /graphql (query Query1, query Query2)`
+
+Set the option to `false` to preserve the default `http.server` span name without this additional context.