runtime(doc): add some docs for file-watcher programs

fixes: #15733

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/editing.txt

@@ -1,4 +1,4 @@
-*editing.txt*   For Vim version 9.1.  Last change: 2024 Oct 13
+*editing.txt*   For Vim version 9.1.  Last change: 2024 Oct 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1058,6 +1058,15 @@ explanation of when the copy is made and when the file is renamed.
 If the creation of a backup file fails, the write is not done.  If you want
 to write anyway add a '!' to the command.
 
+							*file-watcher*
+When you notice issues with programs, that act upon when a buffer is written
+(like inotify, entr or fswatch) or when external applications execute Vim to
+edit the file (like git) and those programs do not seem to notice that the
+original file has been changed, you may want to consider switching the
+'backupcopy' option value to "yes".  This makes sure, Vim writes to the same
+file, that those watcher programs expect, without creating a new file (which
+prevents them from detecting that the file has changed).  See also |crontab|
+
 							*write-permissions*
 When writing a new file the permissions are read-write.  For unix the mask is
 0o666 with additionally umask applied.  When writing a file that was read Vim

runtime/doc/options.txt

@@ -1151,12 +1151,13 @@ A jump table for the options with a short description can be found at |Q_op|.
 	useful for example in source trees where all the files are symbolic or
 	hard links and any changes should stay in the local source tree, not
 	be propagated back to the original source.
-							*crontab*
+								*crontab*
 	One situation where "no" and "auto" will cause problems: A program
 	that opens a file, invokes Vim to edit that file, and then tests if
 	the open file was changed (through the file descriptor) will check the
 	backup file instead of the newly created file.  "crontab -e" is an
-	example.
+	example, as are several |file-watcher| daemons like inotify.  In that
+	case you probably want to switch this option.
 
 	When a copy is made, the original file is truncated and then filled
 	with the new text.  This means that protection bits, owner and

runtime/doc/tags

@@ -7114,6 +7114,7 @@ file-read	insert.txt	/*file-read*
 file-searching	editing.txt	/*file-searching*
 file-type	filetype.txt	/*file-type*
 file-types	filetype.txt	/*file-types*
+file-watcher	editing.txt	/*file-watcher*
 file_readable()	builtin.txt	/*file_readable()*
 filecopy()	builtin.txt	/*filecopy()*
 fileencoding-changed	version6.txt	/*fileencoding-changed*