8178315: nashorn ant build failure with @moduleGraph javadoc tag

Added support for moduleGraph tag

Reviewed-by: sundar, hannesw
diff --git a/nashorn/make/project.properties b/nashorn/make/project.properties
index e47ed11..5626838 100644
--- a/nashorn/make/project.properties
+++ b/nashorn/make/project.properties
@@ -37,7 +37,8 @@
 
 javadoc.option=\
     -tag "implSpec:a:Implementation Requirements:" \
-    -tag "implNote:a:Implementation Note:"
+    -tag "implNote:a:Implementation Note:" \
+    -tag "moduleGraph:a:Module Graph"
 
 # nashorn version information
 nashorn.version=0.1