Update release cycle documentation

Add details on upcoming release cycle adjustments.

Change-Id: I36ade07c87b97c1922d227b27494d7d0d51aa8bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2736864
Commit-Queue: Alex Mineer <[email protected]>
Reviewed-by: Ben Mason <[email protected]>
Cr-Commit-Position: refs/heads/master@{#859816}
diff --git a/docs/process/release_cycle.md b/docs/process/release_cycle.md
index 1f13f7b..9481992 100644
--- a/docs/process/release_cycle.md
+++ b/docs/process/release_cycle.md
@@ -2,6 +2,13 @@
 
 [TOC]
 
+## Upcoming Changes
+
+Chrome is planning to transition to a four week release cycle in Q3 2021; you
+can read more about the new release cycle [here](./release_cycle_new.md).  The
+information below is still relevant until the new cycle is live, at which point
+this page will be replaced by the content at the link above.
+
 ## Overview
 
 Chrome pushes a new stable version to the public every 6 weeks while
@@ -80,3 +87,4 @@
 ## More Info
 
 For more information, see these [guidelines for considering branch dates in project planning](../release_branch_guidance.md).
+