examples: add readme for packages examples

examples/packages/README.md

@@ -0,0 +1,34 @@
+# package examples
+
+This directory contains examples for modules defining packages.
+All modules can be used as templates to create new packages.
+
+Each package module is defined by a directory containing a `default.nix`.
+
+## How to use
+
+All examples are self contained via their own `flake.nix`.
+
+To use multiple packages in a repository, keep only each packages' `default.nix` and put them under a top-level `flake.nix` instead, as shown in the `repo examples` in [/examples](../../examples).
+
+## Usage example
+
+For example, in order to initialize a php-package from `packages/single-language/php-package/`:
+
+```shellSession
+# create new single package repo for php
+$ mkdir my-dream2nix-package
+$ cd my-dream2nix-package
+$ nix flake init -t github:nix-community/dream2nix#templates.php-package
+wrote: /tmp/my-dream2nix-package/flake.nix
+wrote: /tmp/my-dream2nix-package/default.nix
+
+# git add (in case git is used)
+git add .
+
+# interact with the package
+$ nix flake show
+[...]
+$ nix build
+[...]
+```

modules/flake-parts/examples.nix

@@ -20,7 +20,10 @@
 
   dream2nixFlake = import ../../. {};
 
-  packageCategories = readDir ../../examples/packages;
+  packageCategories =
+    lib.filterAttrs
+    (name: type: type == "directory")
+    (readDir ../../examples/packages);
 
   readExamples = dirName: let
     examplesPath = ../../examples/packages + "/${dirName}";