Merge pull request #368 from nokia/metadata-kafka-docs-update

various doc updates

docs/global_flags.md

@@ -307,10 +307,14 @@ The username flag `[-u | --username]` is used to specify the target username as
 
 ### calculate-latency
 
-The `calculate-latency` flag augments subscribe et get responses by calculating the delta between the message timestamp and the receive timestamp.
+The `--calculate-latency` flag augments subscribe et get responses by calculating the delta between the message timestamp and the receive timestamp.
 The resulting message will include 4 extra fields:
 
 * `recv-timestamp`:The receive timestamp in nanoseconds.
 * `recv-time`: The receive time in ISO 8601 date and time representation, extended to include fractional seconds and a time zone offset..
 * `latency-nano`: The difference between the message timestamp and the receive time in nanoseconds.
 * `latency-milli`: The difference between the message timestamp and the receive time in milliseconds.
+
+### metadata
+
+The `[-H | --metadata]` flag adds custom headers to any gRPC request. `gnmic -H header1=value1 -H header2=value2`

docs/user_guide/outputs/kafka_output.md

@@ -25,6 +25,11 @@ outputs:
     # the colon will be replaced with an underscore due to restrictions on the naming of kafka topics.
     # ex: telemetry_bgp_neighbor_state_device1_6030
     topic-prefix: telemetry
+    # starts a sync-producer if set to true.
+    sync-producer: false
+    # required-acks is used in Produce Requests to tell the broker how many replica acknowledgements
+    # it must see before responding. One of `no-response`, `wait-for-local`, `wait-for-all`.
+    required-acks: wait-for-local
     # Kafka SASL configuration
     sasl:
       # SASL user name