doc: fix osd min size

Exact 5 GiB block devices are also considered
as an available device.

Signed-off-by: Satoru Takeuchi <[email protected]>

Author: satoru-takeuchi

doc/cephadm/services/osd.rst

@@ -152,7 +152,7 @@ conditions are met:
 * The device must not be mounted.
 * The device must not contain a file system.
 * The device must not contain a Ceph BlueStore OSD.
-* The device must be larger than 5 GB.
+* The device must be >= 5 GB.
 
 Ceph will not provision an OSD on a device that is not *available*.