Tweak the notes a bit (#3128)

Say a thing about 1.12.8 and HTTP/2
Signed-off-by: Miek Gieben <miek@miek.nl>

notes/coredns-1.6.2.md

@@ -12,6 +12,9 @@ The CoreDNS team has released
 
 This is a bug fix release, but it also features a new plugin called [*azure*](/plugins/azure).
 
+It's compiled with Go 1.12.8 that incorperates fixes for HTTP/2 that may impact you if you use
+[DoH](https://tools.ietf.org/html/rfc8484).
+
 # Plugins
 
 * Add [*azure*](/plugins/azure) to facilitate serving records from Microsoft Azure.