Preparing 1.18.0 release (#1388)

* Prepare CHANGELOG

* Adding cgroup PR

* Updating CHANGELOG

* Fix docs link

Author: eyalkoren

CHANGELOG.asciidoc

@@ -36,7 +36,7 @@ endif::[]
 === Java Agent version 1.x
 
 [[release-notes-1.18.0]]
-==== 1.18.0 - 2020/09/03
+==== 1.18.0 - 2020/09/08
 
 [float]
 ===== Features
@@ -55,7 +55,7 @@ endif::[]
 * Lazily create profiler temporary files {pull}1360[#1360]
 * Convert the followings to Indy Plugins (see details in <<release-notes-1.18.0.rc1, 1.18.0-rc1 relase notes>>): gRPC,
   AsyncHttpClient, Apache HttpClient
-* The agent now collects cgroup memory metrics (see <<metrics>>)
+* The agent now collects cgroup memory metrics (see details in <<metrics-cgroup,Metrics page>>)
 * Update async-profiler to 1.8.1 {pull}1382[#1382]
 
 [float]