Remove another reference to 64-bit systems.
=== Virtual memory
Elasticsearch uses a <<default_fs,`mmapfs`>> directory by
-default for 64bit systems to store its indices. The default operating system limits on mmap
+default to store its indices. The default operating system limits on mmap
counts is likely to be too low, which may result in out of memory exceptions.
On Linux, you can increase the limits by running the following command as
