Switch Developing to say webui-vue

phosphor-webui is End of Life.
Like other documentation switch to webui-vue.

Tested: Pushed to my fork and looked good.

Change-Id: I81d559e7515e24d207856e2cc2b2d0086bf7b3f1
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/DEVELOPING.md b/DEVELOPING.md
index 77cfece..4a481c9 100644
--- a/DEVELOPING.md
+++ b/DEVELOPING.md
@@ -121,9 +121,9 @@
 implementation exists, prefer to make the code correct and clean rather than
 implement a concrete interface.
 
-### phosphor webui
+### webui-vue
 
-The webserver should be capable of hosting phosphor-webui, and implementing the
+The webserver should be capable of hosting webui-vue, and implementing the
 required flows to host the application. In general, all access methods should be
 available to the webui.