Add system file reference dirs

/.vol/234881034/105486 is file #105486 on volume #234881034
https://developer.apple.com/library/archive/qa/qa2001/qa1113.html

/.file/id=6571367.17424234/ is file #17424234 on device #6571367
https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/AccessingFilesandDirectories/AccessingFilesandDirectories.html#//apple_ref/doc/uid/TP40010672-CH3-SW6
https://apple.stackexchange.com/questions/231447/is-it-normal-to-have-a-hidden-file-named-file-in/

Author: mems

Global/macOS.gitignore

@@ -19,6 +19,8 @@ Icon[]
 .PKInstallSandboxManager
 .PKInstallSandboxManager-SystemSoftware
 .hotfiles.btree
+.vol
+.file
 
 # Directories potentially created on remote AFP share
 .AppleDB