pipeline: inputs: memory-metrics: Add threading info

Signed-off-by: Alexa Kreizinger <alexakreizinger@gmail.com>

Author: alexakreizinger

pipeline/inputs/memory-metrics.md

@@ -23,6 +23,11 @@ Fluent Bit v1.x.x
 [3] memory: [1488543159, {"Mem.total"=>1016044, "Mem.used"=>841420, "Mem.free"=>174624, "Swap.total"=>2064380, "Swap.used"=>139888, "Swap.free"=>1924492}]
 ```
 
+## Threading
+
+You can enable the `threaded` setting to run this input in its own
+[thread](../../administration/multithreading.md#inputs).
+
 ### Configuration File
 
 In your main configuration file append the following _Input_ & _Output_ sections: