Update README to include InfiniBand collector

Signed-Off-By: Robert Clark <robert.d.clark@hpe.com>

README.md

@@ -28,6 +28,7 @@ entropy | Exposes available entropy. | Linux
 filefd | Exposes file descriptor statistics from `/proc/sys/fs/file-nr`. | Linux
 filesystem | Exposes filesystem statistics, such as disk space used. | Darwin, Dragonfly, FreeBSD, Linux, OpenBSD
 hwmon | Expose hardware monitoring and sensor data from `/sys/class/hwmon/`. | Linux
+infiniband | Exposes network statistics specific to InfiniBand configurations. | Linux
 loadavg | Exposes load average. | Darwin, Dragonfly, FreeBSD, Linux, NetBSD, OpenBSD, Solaris
 mdadm | Exposes statistics about devices in `/proc/mdstat` (does nothing if no `/proc/mdstat` present). | Linux
 meminfo | Exposes memory statistics. | Darwin, Dragonfly, FreeBSD, Linux