[DOCS] Fix disk.used_percent typo in _cat/nodes docs (#51854)

Corrects an example for the `disk.used_percent` parameter in `_cat/nodes` API.

Author: abia321

docs/reference/cat/nodes.asciidoc

@@ -87,7 +87,7 @@ Used disk space, such as `259.8gb`.
 Available disk space, such as `198.4gb`.
 
 `disk.used_percent`, `dup`, `diskUsedPercent`::
-Used disk space percentage, such as `198.4gb`.
+Used disk space percentage, such as `47`.
 
 `heap.current`, `hc`, `heapCurrent`::
 Used heap, such as `311.2mb`.