KNOWN_BUGS: POP3 issue when reading small chunks

Closes #12063

docs/KNOWN_BUGS

@@ -30,6 +30,7 @@ problems may have been fixed or changed somewhat since this was written.
  3.3 POP3 expects "CRLF.CRLF" eob for some single-line responses
  3.4 AUTH PLAIN for SMTP is not working on all servers
  3.5 APOP authentication fails on POP3
+ 3.6 POP3 issue when reading small chunks
 
  4. Command line
 
@@ -204,6 +205,12 @@ problems may have been fixed or changed somewhat since this was written.
 
  See https://github.com/curl/curl/issues/10073
 
+3.6 POP3 issue when reading small chunks
+
+ CURL_DBG_SOCK_RMAX=4 ./runtests.pl -v 982
+
+ See https://github.com/curl/curl/issues/12063
+
 4. Command line
 
 5. Build and portability issues