Add text in conf file about the config deprecation

Signed-off-by: Shivshankar-Reddy <[email protected]>

valkey.conf

@@ -1354,7 +1354,11 @@ lazyfree-lazy-user-flush yes
 #
 # prefetch-batch-max-size 16
 #
-# NOTE: If you want to test the server speedup using valkey-benchmark, make
+# NOTE:
+# 1. 'io-threads-do-reads' config is depricated and will be removed in the future,
+# please avoid using this option if possible.
+#
+# 2. If you want to test the server speedup using valkey-benchmark, make
 # sure you also run the benchmark itself in threaded mode, using the
 # --threads option to match the number of server threads, otherwise you'll not
 # be able to notice the improvements.