[4.9][bigquery] Adds grpc authentication

axoflow/axosyslog#276

Author: Robert Fekete

content/chapter-destinations/google-bigquery/_index.md

@@ -56,6 +56,8 @@ By default, the messages are sent with one worker, one message per batch, and wi
 
 The `bigquery()` destination has the following options.
 
+{{< include-headless "chunk/grpc-authentication.md" >}}
+
 {{% include-headless "chunk/option-destination-batch-bytes.md" %}}
 
 By default, the `batch-bytes()` option of the `bigquery()` destination is 10 MB. This is an upper limit for the `bigquery()` destination. Note that due to a framework limitation, the batch might be at most 1 message larger than the set limit.