nits: fix comments/improve docs

modules/home-manager/firefox.nix

@@ -173,7 +173,7 @@ in
     '';
 
     sane.packages.extraGuiPkgs = [ package ];
-    # flood the cache to disk to avoid it taking up too much tmp
+    # flush the cache to disk to avoid it taking up too much tmp
     sane.persist.home.byPath."${cfg.browser.cacheDir}" = lib.mkIf (cfg.persistCache != null) {
       store = cfg.persistCache;
     };

modules/persist/default.nix

@@ -160,7 +160,9 @@ let
         store-names;
     in {
       byPath = lib.mkMerge (concatLists [
+        # convert the list-style per-store entries into attrsOf entries
         (applyToAllStores (store: dirToAttrs))
+        # add the `store` attr to everything we ingested
         (applyToAllStores annotateWithStore)
       ]);
     };