Updates in the documentation of google_composer_environment (#11006)

[upstream:0b5921ecf8f3f313e470cfd0f60a1bff74973909]

Signed-off-by: Modular Magician <magic-modules@google.com>

.changelog/11006.txt

@@ -0,0 +1,2 @@
+```release-note:none
+```

website/docs/r/composer_environment.html.markdown

@@ -47,6 +47,11 @@ will not be able to find or manage many of these underlying resources automatica
 resource "google_composer_environment" "test" {
   name   = "example-composer-env"
   region = "us-central1"
+  config {
+    software_config {
+      image_version = "composer-1-airflow-2"
+    }
+  }
 }
 ```
 
@@ -415,14 +420,40 @@ The following arguments are supported:
   They cannot specify Apache Airflow software configuration overrides (they cannot match the regular expression
   `AIRFLOW__[A-Z0-9_]+__[A-Z0-9_]+`), and they cannot match any of the following reserved names:
   ```
+  AIRFLOW_DATABASE_VERSION
   AIRFLOW_HOME
-  C_FORCE_ROOT
+  AIRFLOW_SRC_DIR
+  AIRFLOW_WEBSERVER
+  AUTO_GKE
+  CLOUDSDK_METRICS_ENVIRONMENT
+  CLOUD_LOGGING_ONLY
+  COMPOSER_ENVIRONMENT
+  COMPOSER_GKE_LOCATION
+  COMPOSER_GKE_NAME
+  COMPOSER_GKE_ZONE
+  COMPOSER_LOCATION
+  COMPOSER_OPERATION_UUID
+  COMPOSER_PYTHON_VERSION
+  COMPOSER_VERSION
   CONTAINER_NAME
+  C_FORCE_ROOT
   DAGS_FOLDER
   GCP_PROJECT
+  GCP_TENANT_PROJECT
+  GCSFUSE_EXTRACTED
   GCS_BUCKET
   GKE_CLUSTER_NAME
+  GKE_IN_TENANT
+  GOOGLE_APPLICATION_CREDENTIALS
+  MAJOR_VERSION
+  MINOR_VERSION
+  PATH
+  PIP_DISABLE_PIP_VERSION_CHECK
+  PORT
+  PROJECT_ID
+  PYTHONPYCACHEPREFIX
   SQL_DATABASE
+  SQL_HOST
   SQL_INSTANCE
   SQL_PASSWORD
   SQL_PROJECT