TASK: Improve documentation

* Provide basic usage.
* Provide what's included.

Readme.rst

@@ -19,9 +19,34 @@ Run::
 
     make install
 
-Copy the ``vendor/composer/autoload_classaliasmap.php`` generated by ``composer`` in your TYPO3 installation to ``LegacyClassnames.php`` in the root of this project.
+and copy the ``vendor/composer/autoload_classaliasmap.php`` generated by ``composer`` in your TYPO3
+installation to ``LegacyClassnames.php`` in the root of this project.
 
 Usage
 =====
 
-Will follow.
+Run::
+
+    ./vendor/bin/phpcbf <path>
+
+This will run the auto fixer recursive for ``<path>`` fixing all issues.
+
+Afterwards you should run::
+
+    ./vendor/bin/phpcs <path>
+
+To get information about possible issues that were not autofixed.
+
+What's included?
+================
+
+Currently we can migrate calls to old legacy class names of the TYPO3 core like ``Tx_Extbase...`` to
+new ones like ``\TYPO3\Extbase\...``. This is done for:
+
+- PHPDocuments, like Includes and annotations for IDEs.
+
+- Inheritance like ``extends`` and ``implements``.
+
+- Static calls like ``t3lib_div::`` to ``\TYPO3\Core\Utility\GeneralUtility``.
+
+- Typehints in methods and function like injects.