DOC: update the outdated ROADMAP file

At least the load load balancing was done. Other points are being carried
since 1.5 or so, they should go into the issue tracker with no version
indication.
diff --git a/ROADMAP b/ROADMAP
index f2d00a6..a797b84 100644
--- a/ROADMAP
+++ b/ROADMAP
@@ -1,8 +1,8 @@
-Medium-long term wish list - 2017/11/24
+Medium-long term wish list - updated 2019/06/15
 
 Legend: '+' = done, '-' = todo, '*' = done except doc
 
-1.9 or later :
+2.1 or later :
   - return-html code xxx [ file "xxx" | text "xxx" ] if <acl>
 
   - return-raw  [ file "xxx" | text "xxx" ] if <acl>
@@ -55,8 +55,6 @@
     the server's name or cookie in a header so that the server knows it.
 
 Unsorted :
-  - outgoing log load-balancing (round-robin or hash among multiple servers)
-
   - internal socket for "server XXX frontend:name"
 
   - XML inspection (content-switching for SOAP requests)