Add docs examples

docs/usage/graphql.md

@@ -88,6 +88,12 @@ response = client.query(query: query, variables: variables)
 # do something with the reponse
 ```
 
+To experiment with prerelease features, pass the api_version unstable when initializing the client.
+
+```ruby
+client = ShopifyAPI::Clients::Graphql::Admin.new(session: session, api_version: "unstable")
+```
+
 Want to make calls to the Storefront API? Click [here](graphql_storefront.md)
 
 # Proxy a GraphQL Query

docs/usage/graphql_storefront.md

@@ -39,4 +39,10 @@ response = client.query(query: query)
 # do something with the returned data
 ```
 
+To experiment with prerelease features, pass the api_version unstable when initializing the client.
+
+```ruby
+client = ShopifyAPI::Clients::Graphql::Storefront.new(shop_url, storefront_access_token, api_version: "unstable")
+```
+
 Want to make calls to the Admin API? Click [here](graphql.md)

docs/usage/rest.md

@@ -62,6 +62,13 @@ client.post({
 
 _for more information on the `products` endpoint, [check out our API reference guide](https://shopify.dev/api/admin-rest/unstable/resources/product)._
 
+### Override the `api_version`:
+
+```ruby
+# To experiment with prerelease features, pass the api_version "unstable".
+client = ShopifyAPI::Clients::Rest::Admin.new(session: session, api_version: "unstable")
+```
+
 ## Pagination
 
 This library also supports cursor-based pagination for REST Admin API requests. [Learn more about REST request pagination](https://shopify.dev/api/usage/pagination-rest).