doc: remove incorrect synchronous label

fsPromises.rm() is not synchronous.

PR-URL: #35561
Reviewed-By: Daijiro Wachi <[email protected]>
Reviewed-By: Ben Coe <[email protected]>
Reviewed-By: Jiawen Geng <[email protected]>
Reviewed-By: Harshitha K P <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Rich Trott <[email protected]>

Author: cjihrig

doc/api/fs.md

@@ -5540,8 +5540,8 @@ added: REPLACEME
     retries. This option is ignored if the `recursive` option is not `true`.
     **Default:** `100`.
 
-Synchronously removes files and directories (modeled on the standard POSIX `rm`
-utility). Resolves the `Promise` with no arguments on success.
+Removes files and directories (modeled on the standard POSIX `rm` utility).
+Resolves the `Promise` with no arguments on success.
 
 ### `fsPromises.stat(path[, options])`
 <!-- YAML