doc: Reorganise images and update links

Change-Id: I679d1499376a524bef1cfc33df995b0a719b5ac8
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/components/sdei.rst b/docs/components/sdei.rst
index 7b6cc91..845a295 100644
--- a/docs/components/sdei.rst
+++ b/docs/components/sdei.rst
@@ -26,7 +26,7 @@
 at EL2 and an event dispatch resulting from the triggering of a bound interrupt.
 A commentary is provided below:
 
-.. image:: ../plantuml/sdei_general.svg
+.. image:: ../resources/diagrams/plantuml/sdei_general.svg
 
 As part of initialisation, the SDEI client binds a Non-secure interrupt [1], and
 the SDEI dispatcher returns a platform dynamic event number [2]. The client then
@@ -234,7 +234,7 @@
 The following figure depicts a scenario involving explicit dispatch of SDEI
 event. A commentary is provided below:
 
-.. image:: ../plantuml/sdei_explicit_dispatch.svg
+.. image:: ../resources/diagrams/plantuml/sdei_explicit_dispatch.svg
 
 As part of initialisation, the SDEI client registers a handler for a platform
 event [1], enables the event [3], and unmasks the current PE [5]. Note that,