feature: Add example 2 to docs

Author: denisart

docs/source/examples.rst

@@ -4,4 +4,5 @@ Usage Examples
 .. toctree::
   :maxdepth: 2
 
-  examples/list_of_objects
+  examples/list_of_objects
+  examples/with_gql

docs/source/examples/with_gql.rst

@@ -0,0 +1,86 @@
+With gql
+========
+
+It is the simple example for usage of **graphql-query** with `gql 3 <https://gql.readthedocs.io/en/stable/index.html>`_.
+How to install **gql 3** you can see `here <https://gql.readthedocs.io/en/stable/intro.html#installation>`_.
+
+Basic Usage
+-----------
+
+For the Basic usage of **gql 3** with **graphql-query** you can running the following code
+
+.. code-block:: python
+
+  from gql import Client, gql
+  from gql.transport.aiohttp import AIOHTTPTransport
+  from graphql_query import Operation, Query
+
+  # Select your transport with a defined url endpoint
+  transport = AIOHTTPTransport(url="https://countries.trevorblades.com/")
+
+  # Create a GraphQL client using the defined transport
+  client = Client(transport=transport, fetch_schema_from_transport=True)
+
+  # generating of GraphQL query string with graphql_query
+  getContinents = Operation(
+      type="query",
+      name="getContinents",
+      queries=[Query(name="continents", fields=["code", "name"])]
+  )
+
+  # Provide a GraphQL query
+  query = gql(getContinents.render())
+
+  # Execute the query on the transport
+  result = client.execute(query)
+  print(result)
+  # {'continents': [{'code': 'AF', 'name': 'Africa'}, {'code': 'AN', 'name': 'Antarctica'}, {'code': 'AS', 'name': 'Asia'}, {'code': 'EU', 'name': 'Europe'}, {'code': 'NA', 'name': 'North America'}, {'code': 'OC', 'name': 'Oceania'}, {'code': 'SA', 'name': 'South America'}]}
+
+Using variables
+---------------
+
+GraphQL variables it is easy
+
+.. code-block:: python
+
+  from gql import Client, gql
+  from gql.transport.aiohttp import AIOHTTPTransport
+  from graphql_query import Argument, Operation, Query, Variable
+
+  # Select your transport with a defined url endpoint
+  transport = AIOHTTPTransport(url="https://countries.trevorblades.com/")
+
+  # Create a GraphQL client using the defined transport
+  client = Client(transport=transport, fetch_schema_from_transport=True)
+
+  # generating of GraphQL query string with graphql_query
+  code = Variable(name="code", type="ID!")
+
+  getContinentName = Operation(
+      type="query",
+      name="getContinentName",
+      variables=[code],
+      queries=[
+          Query(
+              name="continent",
+              arguments=[Argument(name="code", value=code)],
+              fields=["name"]
+          )
+      ]
+  )
+
+  query = gql(getContinentName.render())
+
+  params = {"code": "EU"}
+
+  # Get name of continent with code "EU"
+  result = client.execute(query, variable_values=params)
+  print(result)
+  # {'continent': {'name': 'Europe'}}
+
+  params = {"code": "AF"}
+
+  # Get name of continent with code "AF"
+  result = client.execute(query, variable_values=params)
+  print(result)
+  # {'continent': {'name': 'Africa'}}