rust: macros: indent list item in module!'s docs

Like commit e516211f61 ("rust: macros: indent list item in `paste!`'s
docs"), but for `module!`.

Reviewed-by: Trevor Gross <tmgross@umich.edu>
Link: https://lore.kernel.org/r/20240725184644.135185-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/macros/lib.rs

@@ -94,7 +94,7 @@ use proc_macro::TokenStream;
 ///   - `license`: ASCII string literal of the license of the kernel module (required).
 ///   - `alias`: array of ASCII string literals of the alias names of the kernel module.
 ///   - `firmware`: array of ASCII string literals of the firmware files of
-/// the kernel module.
+///     the kernel module.
 #[proc_macro]
 pub fn module(ts: TokenStream) -> TokenStream {
     module::module(ts)