fix(files.md): override Cargo.toml in example (#1307)

- override existing `Cargo.toml` file with `-f` flag for `save` in example
- Point out `inc` is available through the `nu_plugin_inc`

Author: qdm12

cookbook/files.md

@@ -24,9 +24,11 @@ Make the edit to the version number and save it.
 _Note: running this command should work but it will reorder the toml file alphabetically by section._
 
 ```nu
-open Cargo.toml | upsert package.version { |p| $p | get package.version | inc --patch } | save Cargo.toml
+open Cargo.toml | upsert package.version { |p| $p | get package.version | inc --patch } | save -f Cargo.toml
 ```
 
+Note: `inc` is available through the plugin `nu_plugin_inc`.
+
 Output
 _none_