Misc changes

Fixing gnbsim reference
Adding sdcore logo image
separated configuration section

Change-Id: Ib6ec73d8528a3e197c0e19be6a3ee7c1942c6211
diff --git a/developer/gnbsim.rst b/developer/gnbsim.rst
index 951275a..0ef97f1 100644
--- a/developer/gnbsim.rst
+++ b/developer/gnbsim.rst
@@ -1,3 +1,5 @@
+.. _gNB-Simulator:
+
 gNB Simulator
 =============