Update Get Started Guide

doc/GSG/intro_gsg.rst

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 .. _Intro_gsg:
 
 
-|short_name| is a runtime-based parallel programming model for C++ code that uses threads. 
-It enables you to simplify parallel programming by breaking 
-computation into parallel running tasks. 
-The library consists of a template-based runtime library to help you harness the latent performance
-of multi-core processors. Use |short_name| to write scalable applications that:
+|full-name| is a runtime-based parallel programming model for C++ code that uses threads. 
+It consists of a template-based runtime library to help you harness the latent performance of multi-core processors.
 
+oneTBB enables you to simplify parallel programming by breaking computation into parallel running tasks. Within a single process, 
+parallelism is carried out through threads, an operating system mechanism that allows the same or different sets of instructions 
+to be executed simultaneously.
 
-- Specify logical parallel structure instead of threads
-- Emphasize data parallel programming
-- Take advantage of concurrent collections and parallel algorithms
+
+.. image:: Images/how-oneTBB-works.png
+
+
+Use oneTBB to write scalable applications that:
+
+* Specify logical parallel structure instead of threads
+* Emphasize data-parallel programming
+* Take advantage of concurrent collections and parallel algorithms
+
+oneTBB supports nested parallelism as well. It means that you can use the library without being worried about overloading a computer.