doc: add inbuilt graph nodes data flow

Added diagram to depict the data flow between inbuilt
graph nodes.

In order to avoid graphviz package dependency to DPDK
documentation, manual step added to create a svg file
from the dot file. The details for the same is documented
in graph_inbuilt_node_flow.svg as a comment.

Signed-off-by: Jerin Jacob <jerinj@marvell.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

doc/guides/prog_guide/graph_lib.rst

@@ -394,8 +394,16 @@ to enable fastpath services.
 Inbuilt Nodes
 -------------
 
-DPDK provides a set of nodes for data processing. The following section
-details the documentation for the same.
+DPDK provides a set of nodes for data processing. The following diagram depicts
+inbuilt nodes data flow.
+
+.. _figure_graph_inbuit_node_flow:
+
+.. figure:: img/graph_inbuilt_node_flow.*
+
+   Inbuilt nodes data flow
+
+Following section details the documentation for individual inbuilt node.
 
 ethdev_rx
 ~~~~~~~~~