TODO: Remove item related to Client Characteristic Configuration

Client Characteristic Configuration is already implemented in the
attribute server. Implementation in the attribute client is still
missing.
diff --git a/TODO b/TODO
index 45ecb09..cf37179 100644
--- a/TODO
+++ b/TODO
@@ -188,15 +188,6 @@
   Priority: Low
   Complexity: C2
 
-- Implement Client Characteristic Configuration support in the attribute
-  server to manage indications and notications. This is a per client attribute
-  to control how the client wants to receive reports of changes in a given
-  characteristic value.
-  See Volume 3, Part G, section 3.3.3.3 for more information
-
-  Priority: Low
-  Complexity: C2
-
 - Define attribute server API. External applications needs to register,
   change attributes and to be notified about changes. Example: Proximity,
   Time and Alert Profiles. "Local Service hierarchy" in the attribute-api