Add missing index

inst/doc/faq.md

@@ -39,6 +39,7 @@ This document intends to be the first reference for any doubts that you may have
    6. [Errors using a new cluster (setting Nord3)](#6-errors-using-a-new-cluster-setting-nord3)
    7. [Start() fails retrieving data](#7-start-fails-retrieving-data)  
    8. [Error 'caught segfault' when job submitted to HPCs](#8-error-caught-segfault-when-job-submitted-to-hpcs)
+   9. [White lines on the figure of interpolated irregular data](#9-white-lines-on-the-figure-of-interpolated-irregular-data)
 
 
 ## 1. How to