Update Files chapter of Emacs manual.

Plus miscellaneous minor speling fixes in other manual files.

* doc/emacs/files.texi (File Names, Visiting, Interlocking): Copyedits.
(Backup Copying): backup-by-copying-when-mismatch is now t.
(Customize Save): Fix description of require-final-newline.
(Reverting): Note that revert-buffer can't be undone.  Mention VC.
(Auto Save Control): Clarify.
(File Archives): Add 7z.
(Remote Files): ange-ftp-make-backup-files defaults to nil.

* doc/emacs/arevert-xtra.texi (Autorevert): Copyedits.

admin/FOR-RELEASE

@@ -151,7 +151,7 @@ TUTORIAL.zh
 abbrevs.texi      
 ack.texi          
 anti.texi
-arevert-xtra.texi
+arevert-xtra.texi cyd
 basic.texi        cyd
 buffers.texi      
 building.texi     
@@ -167,7 +167,7 @@ emacs.texi
 emacs-xtra.texi
 emerge-xtra.texi
 entering.texi     cyd
-files.texi        
+files.texi        cyd
 fixit.texi        
 fortran-xtra.texi 
 frames.texi       
@@ -175,7 +175,7 @@ glossary.texi
 help.texi         cyd
 indent.texi       
 killing.texi      cyd
-kmacro.texi       
+kmacro.texi       cyd
 macos.texi        
 maintaining.texi  
 major.texi