doc/man: supplant "wsync" with "nowsync" as the default

Change the default from "wsync" to "nowsync". "nowsync" has been the
default since kernel version 5.16.

This information was reported on
https://pad.ceph.com/p/Report_Documentation_Bugs by Benjamin Mare on 07
Oct 2024.

The commit relevant to this change can be seen here, in Linus's main
branch:
torvalds/linux@f7a67b4

Co-authored-by: Anthony D'Atri <[email protected]>
Signed-off-by: Zac Dover <[email protected]>

Author: zdover23

doc/man/8/mount.ceph.rst

@@ -192,12 +192,13 @@ Advanced
 :command:`wsync`
     Execute all namespace operations synchronously. This ensures that the
     namespace operation will only complete after receiving a reply from
-    the MDS. This is the default.
+    the MDS. 
 
 :command:`nowsync`
     Allow the client to do namespace operations asynchronously. When this
     option is enabled, a namespace operation may complete before the MDS
-    replies, if it has sufficient capabilities to do so.
+    replies, if it has sufficient capabilities to do so. This has been the
+    default since kernel version 5.16.
 
 :command:`crush_location=x`
     Specify the location of the client in terms of CRUSH hierarchy (since 5.8).