restructuredtext: mention auto-complete-rst to README

layers/+lang/restructuredtext/README.org

@@ -6,6 +6,8 @@
  - [[#description][Description]]
    - [[#features][Features]]
  - [[#install][Install]]
+ - [[#configuration][Configuration]]
+   - [[#auto-complete][Auto-complete]]
 
 * Description
 The layer adds ReStructuredText (ReST) support to Spacemacs and adds some
@@ -17,9 +19,16 @@ Note: to add =Sphinx= specific support use the layer =sphinx=.
 - =rst= files are supported via Emacs built-in =rst.el=.
 - Lists are inserted by new functions. 
 - Directives can be inserted easily.
+- auto-completion for directives and options via =auto-complete-rst=.
+- snippet support via =yasnippet=.
 
 * Install
 To use this configuration layer, add it to your =~/.spacemacs=. You will need to
 add =restructuredtext= to the existing =dotspacemacs-configuration-layers= list
 in this file.
 
+* Configuration
+** Auto-complete
+For now =auto-complete-rst= only works with sphinx 1.4.9 and lower.
+New 1.5 release (as from December 2016) is not yet supported.
+