doc: clarify maxRSS unit in process.resourceUsage()

PR-URL: nodejs#59511
Fixes: nodejs#59508
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: himself65

doc/api/process.md

@@ -3642,7 +3642,7 @@ added: v12.6.0
   * `systemCPUTime` {integer} maps to `ru_stime` computed in microseconds.
     It is the same value as [`process.cpuUsage().system`][process.cpuUsage].
   * `maxRSS` {integer} maps to `ru_maxrss` which is the maximum resident set
-    size used in kilobytes.
+    size used in kibibytes (1024 bytes).
   * `sharedMemorySize` {integer} maps to `ru_ixrss` but is not supported by
     any platform.
   * `unsharedDataSize` {integer} maps to `ru_idrss` but is not supported by