Docs: Bringing PlantUML Back

Change-Id: I984b43a522e4a8668f25acf1a2d55bb37a879693
Signed-off-by: Elena Uziunaite <elena.uziunaite@arm.com>
diff --git a/docs/conf.py b/docs/conf.py
index dd8d4c8..468e62f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -61,6 +61,10 @@
 
 intersphinx_disabled_reftypes = ["*"]
 
+#PlantUML
+if 'PLANTUML_JAR_PATH' in os.environ:
+    plantuml = 'java -jar ' + os.environ['PLANTUML_JAR_PATH']
+
 # Make auto section labels generated be prefixed with file name.
 autosectionlabel_prefix_document=True
 # Add auto section label for level 2 headers only.