KNOWN_BUGS: hyper memory-leaks

Closes #10803

docs/KNOWN_BUGS

@@ -12,6 +12,7 @@ check the changelog of the current development status, as one or more of these
 problems may have been fixed or changed somewhat since this was written.
 
  1. HTTP
+ 1.1 hyper memory-leaks
  1.5 Expect-100 meets 417
 
  2. TLS
@@ -108,6 +109,12 @@ problems may have been fixed or changed somewhat since this was written.
 
 1. HTTP
 
+1.1 hyper memory-leaks
+
+ Building curl with the hyper backend causes mysterious memory-leaks
+
+ https://github.com/curl/curl/issues/10803
+
 1.5 Expect-100 meets 417
 
  If an upload using Expect: 100-continue receives an HTTP 417 response, it