dnsdist: Document libedit Ctrl-R workaround for CentOS 6

Fixes #3227.

diff --git a/pdns/README-dnsdist.md b/pdns/README-dnsdist.md
index 2874d3acc162eb14f8eff4d7de69bf0cf1f46f43..391e8cf9f90c56382b24df4281d73fc6817106db 100644 (file)
--- a/pdns/README-dnsdist.md
+++ b/pdns/README-dnsdist.md
@@ -704,6 +704,13 @@ Please note that, without libsodium support, 'makeKey()' will return
 setKey("plaintext") and the communication between the client and the
 server will not be encrypted.
 
+Some versions of libedit, notably the CentOS 6 one, may require the following
+addition to ~/.editrc in order to support searching through the history:
+
+```
+bind "^R" em-inc-search-prev
+```
+
 ACL, who can use dnsdist
 ------------------------
 For safety reasons, by default only private networks can use `dnsdist`, see below