Update gateway passthrough with otlphttp method

Signed-off-by: Dani Louca <[email protected]>

Author: dloucasfx

gdi/opentelemetry/components/otlphttp-exporter.rst

@@ -124,6 +124,7 @@ By default, gzip compression is turned on. To turn it off use the following conf
       ...
       compression: none
 
+.. _otlphttp-exporter-token-passthrough:
 
 Associate passthroughs to an access token
 ------------------------------------------

gdi/opentelemetry/deployment-modes.rst

@@ -101,6 +101,13 @@ Learn more at :ref:`signalfx-exporter`.
 
 .. _collector-current-mode:
 
+Token usage with the otlphttp exporter
+-------------------------------------------------------------------------------
+
+If any of your Collectors in agent mode is exporting data to the otlp receiver running on the gateway and you want to use the token set at the source instead of the gateway's token, uncomment ``include_metadata: true`` :new-page:`from the default gateway config <https://github.com/signalfx/splunk-otel-collector/blob/main/cmd/otelcol/config/collector/gateway_config.yaml>` 
+
+Learn more at :ref:`otlphttp-exporter-token-passthrough`.
+
 What mode is my Collector deployed as? How can I change it?
 ======================================================================