add brief description in the docs

Author: marcobarilari

docs/functions_description.md

@@ -10,6 +10,7 @@
 	* 1.6. [eyeTracker](#eyeTracker)
 	* 1.7. [standByScreen](#standByScreen)
 	* 1.8. [waitForTrigger](#waitForTrigger)
+	* 1.9  [readOutputFilter](#readOutputFilter)
 * 2. [Keyboard functions: response collection and aborting experiment](#Keyboardfunctions:responsecollectionandabortingexperiment)
 	* 2.1. [testKeyboards](#testKeyboards)
 	* 2.2. [getResponse](#getResponse)
@@ -73,6 +74,9 @@ It shows a basic one-page instruction stored in `cfg.task.instruction` and wait
 Counts a certain number of triggers coming from the mri/scanner before returning.
 Requires number of triggers to wait for.
 
+### 1.9 <a name='readOutputFilter'></a>readOutputFilter
+
+At the end of your experiment will display in the command window part of the `*events.tsv` file filterd by an element (e.g. 'trigger').
 
 ##  2. <a name='Keyboardfunctions:responsecollectionandabortingexperiment'></a>Keyboard functions: response collection and aborting experiment
 
@@ -120,4 +124,4 @@ Define the parameters of the fixation cross in `cfg` and `expParameters` and thi
 
 ##  4. <a name='Drawingdots'></a>Drawing dots
 
-##  5. <a name='Drawingapertures'></a>Drawing apertures
+##  5. <a name='Drawingapertures'></a>Drawing apertures