docs: replace references to genautocomplete with the new name completion

cmd/genautocomplete/genautocomplete.go

@@ -1,4 +1,4 @@
-// Package genautocomplete provides the genautocomplete command.
+// Package genautocomplete provides the completion command.
 package genautocomplete
 
 import (

cmd/genautocomplete/genautocomplete_bash.go

@@ -20,7 +20,7 @@ Generates a bash shell autocompletion script for rclone.
 
 By default, when run without any arguments, 
 
-    rclone genautocomplete bash
+    rclone completion bash
 
 the generated script will be written to
 

cmd/genautocomplete/genautocomplete_fish.go

@@ -21,7 +21,7 @@ Generates a fish autocompletion script for rclone.
 This writes to /etc/fish/completions/rclone.fish by default so will
 probably need to be run with sudo or as root, e.g.
 
-    sudo rclone genautocomplete fish
+    sudo rclone completion fish
 
 Logout and login again to use the autocompletion scripts, or source
 them directly

cmd/genautocomplete/genautocomplete_zsh.go

@@ -21,7 +21,7 @@ Generates a zsh autocompletion script for rclone.
 This writes to /usr/share/zsh/vendor-completions/_rclone by default so will
 probably need to be run with sudo or as root, e.g.
 
-    sudo rclone genautocomplete zsh
+    sudo rclone completion zsh
 
 Logout and login again to use the autocompletion scripts, or source
 them directly