fix readme about expose memory statistics

Signed-off-by: joey <zchengjoey@gmail.com>

README.md

@@ -193,7 +193,7 @@ interrupts | Exposes detailed interrupts statistics. | Linux, OpenBSD
 ksmd | Exposes kernel and system statistics from `/sys/kernel/mm/ksm`. | Linux
 lnstat | Exposes stats from `/proc/net/stat/`. | Linux
 logind | Exposes session counts from [logind](http://www.freedesktop.org/wiki/Software/systemd/logind/). | Linux
-meminfo\_numa | Exposes memory statistics from `/proc/meminfo_numa`. | Linux
+meminfo\_numa | Exposes memory statistics from `/sys/devices/system/node/node[0-9]*/meminfo`, `/sys/devices/system/node/node[0-9]*/numastat`. | Linux
 mountstats | Exposes filesystem statistics from `/proc/self/mountstats`. Exposes detailed NFS client statistics. | Linux
 network_route | Exposes the routing table as metrics | Linux
 perf | Exposes perf based metrics (Warning: Metrics are dependent on kernel configuration and settings). | Linux