Add big fat warning to README

Recommend against using this module.

README.md

@@ -3,6 +3,19 @@
 Current context for LoopBack applications, based on
 node-continuation-local-storage.
 
+## WARNING
+
+The module node-continuation-local-storage is known to have many problems,
+see e.g. [issue #59](https://github.com/othiym23/node-continuation-local-storage/issues/59).
+As a result, loopback-context does not work in many situations, as can be
+seen from issues reported in LoopBack's
+[issue tracker](https://github.com/strongloop/loopback/issues?utf8=%E2%9C%93&q=is%3Aissue%20getCurrentcontext).
+
+**We recommend AGAINST using this module.**
+
+If you are running on Node v6, you can try the new alternative
+[cls-hooked](https://github.com/Jeff-Lewis/cls-hooked).
+
 ## Usage
 
 1) Add `per-request` middleware to your
@@ -31,4 +44,6 @@ MyModel.myMethod = function(cb) {
 });
 ```
 
-See also https://docs.strongloop.com/display/APIC/Using+current+context
+See the official LoopBack
+[documentation](https://docs.strongloop.com/display/APIC/Using+current+context)
+for more details.