Updated roadmap to reflect dates for 2.8 (#48626)

* Updated roadmap to reflect dates for 2.8

docs/docsite/rst/roadmap/ROADMAP_2_8.rst

@@ -2,7 +2,8 @@
 Ansible 2.8
 ===========
 
-.. contents:: Topics
+.. contents::
+   :local:
 
 Release Schedule
 ----------------
@@ -10,7 +11,22 @@ Release Schedule
 Expected
 ========
 
-- 2019Q1 General Availability
+PRs must be raised well in advance of the dates below to have a chance of being included in this Ansible release.
+
+- 2019-03-14 Alpha 1 **Core freeze**
+
+  No new features to ``support:core`` code.
+  Includes no new options to existing Core modules
+- 2019-03-21 Beta 1 **Feature freeze**
+
+  No new functionality (including modules/plugins) to any code
+- 2019-04-04 Release Candidate 1
+- 2019-04-11 Release Candidate 2 (if needed)
+- 2019-04-18 Release Candidate 3 (if needed)
+- 2019-04-25 Release Candidate 4 (if needed)
+- 2019-05-02 Release
+
+
 
 Release Manager
 ---------------