chore(spell-checker): update ignore list to include statx and behaviour

Add "statx" (a Linux system call name) and "behaviour" (potential spelling variant) to the spell-checker ignore comment in the rm utility's Linux platform code, preventing false positives in linting.

Author: mattsu2020

src/uu/rm/src/platform/linux.rs

@@ -5,7 +5,7 @@
 
 // Linux-specific implementations for the rm utility
 
-// spell-checker:ignore fstatat unlinkat
+// spell-checker:ignore fstatat unlinkat statx behaviour
 
 use indicatif::ProgressBar;
 use std::ffi::OsStr;