add missing err comment

Author: hendrikmaus

asyncgit/src/error.rs

@@ -85,6 +85,7 @@ pub enum Error {
 	#[error("git hook error: {0}")]
 	Hooks(#[from] git2_hooks::HooksError),
 
+	///
 	#[error("sign builder error: {0}")]
 	SignBuilder(#[from] crate::sync::sign::SignBuilderError),