Adding vnaas link to API docs

Change-Id: Ib34b859a94174e067c6b0b83e1dd0cac0d5fad3d
diff --git a/docs/operate/rest_apis.md b/docs/operate/rest_apis.md
index 9fe2287..d507149 100644
--- a/docs/operate/rest_apis.md
+++ b/docs/operate/rest_apis.md
@@ -17,3 +17,4 @@
 * [Example Service](https://guide.opencord.org/{{ book.branch }}/api/xos/#/exampleservice)
 * [vEE](https://guide.opencord.org/{{ book.branch }}/api/xos/#/vee)
 * [vEG](https://guide.opencord.org/{{ book.branch }}/api/xos/#/veg)
+* [vnaas](https://guide.opencord.org/{{ book.branch }}/api/xos/#/vnaas)