KNOWN_BUGS: DoH leaks memory after followlocation

Closes #4592
diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index 8df986c..1bd0c92 100644
--- a/docs/KNOWN_BUGS
+++ b/docs/KNOWN_BUGS
@@ -99,6 +99,7 @@
  11.5 Connection information when using TCP Fast Open
  11.6 slow connect to localhost on Windows
  11.7 signal-based resolver timeouts
+ 11.8 DoH leaks memory after followlocation
 
  12. LDAP and OpenLDAP
  12.1 OpenLDAP hangs after returning results
@@ -703,6 +704,9 @@
  Also, alarm() provides timeout resolution only to the nearest second. alarm
  ought to be replaced by setitimer on systems that support it.
 
+11.8 DoH leaks memory after followlocation
+
+ https://github.com/curl/curl/issues/4592
 
 12. LDAP and OpenLDAP