Add the supported version of eclipse to the README doc (#16)

README.md

diff --git a/README.md b/README.md
index d8721d6..f470817 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,8 @@
 
 ## Installation
 
+This plugin was tested with Eclipse Mars (4.5) but should also work with Eclipse Neon (4.6).
+
    * Start Eclipse
    * Select "Help" > "Install Software"
    * Add the update