add note about flush flag

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

core/commands/files/files.go

@@ -27,6 +27,14 @@ var FilesCmd = &cmds.Command{
 		Tagline: "Manipulate unixfs files.",
 		ShortDescription: `
 Files is an API for manipulating ipfs objects as if they were a unix filesystem.
+
+Note:
+Most of the subcommands of 'ipfs files' accept the '--flush' flag. Use caution
+when using this flag, It will improve performance for large numbers of file
+operations, but it does so at the cost of consistency guarantees. If the daemon
+is unexpectedly killed before running 'ipfs files flush' on the files in question,
+then data may be lost. This also applies to running 'ipfs repo gc' concurrently
+with '--flush=false' operations.
 `,
 	},
 	Options: []cmds.Option{