Update eclipse.md (#1225)

Clarifying that it's no longer possible to make changes in the Core Framework for 2.5.x.

Signed-off-by: Mark Theiding <mark.theiding@gmail.com>

developers/ide/eclipse.md

@@ -47,7 +47,7 @@ This guide describes the steps to setup Eclipse and how to debug an add-on in Ec
 
     ::: warning Attention
     Select `2.5.x` if you want to develop for 2.5.x.
-    The Core Framework only has a master branch (3.0 development).
+    The Core Framework only has a master branch (3.0 development), which means you can no longer make Core Framework changes for a 2.5.x system.
     :::
 
 1. Click `Next>`, verify/modify Root and install folder name. Click on `Show all variables` to open the window shown below.