[release-notes] Add link to technical details of multimonitor refresh rates

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 3c873b7c554f937aab2a7f85f401d71e93546f73
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Thu Sep 3 17:39:54 2020 -0500

    Add link to technical details of multimonitor refresh rates
    
    Without the link, it's hard to know what this change really means. But
    it's too technical to really explain within the release notes itself. So
    let's just add a link.

 help/C/index.page | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/help/C/index.page b/help/C/index.page
index cd5d0eb8..78be9000 100644
--- a/help/C/index.page
+++ b/help/C/index.page
@@ -64,9 +64,10 @@
 
   <section>
     <title>Better Multi-Monitor Support</title>
-    <p>GNOME Shell can now drive multiple monitors with different refresh
-    rates, making sure that you get the best possible experience out of your
-    desktop.</p>
+    <p>GNOME Shell can now <link 
href="https://blogs.gnome.org/shell-dev/2020/07/02/splitting-up-the-frame-clock/";>
+    drive multiple monitors with different refresh rates</link>, making sure
+    that you get the best possible experience out of your
+    desktop. This improvement is only available in Wayland sessions.</p>
   </section>
 
   <section>