docs: fix link for tutorial, tweak simulated data wording

doc/source/simulated_data.rst

 .. _simulated-data:
 
-Simulated Data Generation
-=========================
+Simulated Data
+===============
 
-WRITEME
+See :ref:`simulated-data-tutorial`.

doc/source/tutorials/gstlal_fake_data_overview.rst

-Documentation for creating fake data
-====================================
+.. _simulated-data-tutorial:
+
+Tutorial: Generation of simulated data
+=======================================
 
 Introduction
 ------------