Add missing sections

Author: pitr-ch

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Release v1.1.9 (5 Jun 2021)
 
+concurrent-ruby:
+
 * (#866) Child promise state not set to :pending immediately after #execute when parent has completed 
 * (#905, #872) Fix RubyNonConcurrentPriorityQueue#delete method
 * (2df0337d) Make sure locks are not shared on shared when objects are dup/cloned
@@ -10,6 +12,8 @@
 
 ## Release v1.1.8 (20 January 2021)
 
+concurrent-ruby:
+
 * (#885) Fix race condition in TVar for stale reads 
 * (#884) RubyThreadLocalVar: Do not iterate over hash which might conflict with new pair addition