add docstrings

crates/pacdef_core/src/grouping/group.rs

@@ -137,6 +137,9 @@ impl Group {
         })
     }
 
+    /// Add the new `packages` to the group file under the section `section_header`. If
+    /// the section header does not yet exist, it is created. The packages are written
+    /// in the provided order immediately after the header.
     pub(crate) fn save_packages(&self, section_header: &str, packages: &[Package]) -> Result<()> {
         let mut content = read_to_string(&self.path)
             .with_context(|| format!("reading existing file contents from {:?}", &self.path))?;

crates/pacdef_core/src/grouping/mod.rs

@@ -1,3 +1,13 @@
+/*!
+This module reflects the relationship between groups, sections / backends and
+packages.
+
+A ['Group'] contains one (strictly spoken zero, but this doesn't make sense) or
+more ['Section']s, which relate to individual backends. Each section contains
+one (strictly spoken zero) or more ['Package']s. On start-up `pacdef` will load
+all groups using ['Group::load'], which in turn will get all packages from all
+sections.
+*/
 mod group;
 mod package;
 mod section;