docs: Add SDEI dispatcher documentation

The document includes SDEI sequence diagrams that are generated using
PlantUML [1].

A shell script is introduced to generate SVG files from PlantUML files
supplied in arguments.

[1] http://plantuml.com/PlantUML_Language_Reference_Guide.pdf

Change-Id: I433897856810bf1927f2800a7b2b1d81827c69b2
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/docs/plantuml/plantuml_to_svg.sh b/docs/plantuml/plantuml_to_svg.sh
new file mode 100755
index 0000000..0bf8588
--- /dev/null
+++ b/docs/plantuml/plantuml_to_svg.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# Convert all PlantUML files in this directory to SVG files. The plantuml_jar
+# environment variable must be set to the path to PlantUML JAR file.
+
+if [ -z "$plantuml_jar" ]; then
+	echo "Usage: plantuml_jar=/path/to/plantuml.jar $0 *.puml" >&2
+	exit 1
+fi
+
+java -jar "$plantuml_jar" -nometadata -tsvg "$@"
+
+# vim:set noet sts=8 tw=80: