docs: added documentation, enforced documentation

src/build.rs

@@ -2,6 +2,7 @@ use std::error::Error;
 use std::path::Path;
 use std::process::Command;
 
+/// Build a Debian source package (to a .dsc)
 pub fn build_source_package(cwd: Option<&Path>) -> Result<(), Box<dyn Error>> {
     let cwd = cwd.unwrap_or_else(|| Path::new("."));