Update usage instructions. Fixes #296 (#306)

README.md

@@ -31,8 +31,22 @@ haxelib install dox
 abstract rtti xml generation. You'll also need an up-to-date haxelib
 (requires support for `classPath` in _haxelib.json_)
 
-1. Compile all relevant code with Haxe using `haxe -xml docs/doc.xml -D doc-gen`.
-2. Invoke `haxelib run dox -i docs`, where dir points to the .xml file(s) generated by step 1.
+1. Compile the code to be included in the documentation using:
+   ```sh
+   haxe -xml docs/doc.xml -D doc-gen [LIBS] <CLASSPATH> <TARGET> <PACKAGE_NAME>
+   ```
+   E.g.
+   ```sh
+   haxe -xml docs/doc.xml -D doc-gen --lib hxargs --classpath src -java bin my.aweseome.package
+   ```
+2. Generate the HTML pages using:
+   ```sh
+   haxelib run dox -i <INPUT_DIR>
+   ```
+   ...where `input_dir` points to the directory containing the generated .xml file(s) of the previous step, i.e.
+   ```sh
+   haxelib run dox -i docs
+   ```
 
 **:clipboard: For more details, custom theme creation and options [check out the Dox wiki](https://github.com/HaxeFoundation/dox/wiki/)**