Document translation reporting

Fixes #947
Signed-off-by: Michal Čihař <michal@cihar.com>

docs/devel/index.rst

@@ -10,3 +10,4 @@ benefits. It's only up to you how much of that you will use.
     translations
     review
     share
+    reporting

docs/devel/reporting.rst

+Translation progress reporting
+==============================
+
+It is often useful to be able to see how translation progresses over given
+period. For this purpose Weblate includes reporting features, where you can
+obtain summaries of contributions to given component over time. You can find
+the reporting tool in the :guilabel:`Tools` menu for a translation component:
+
+.. image:: ../images/reporting.png
+    
+Several reporting tools are available on this page and all can produce output
+in HTML, reStructuredText or JSON. The first two formats are suitable for
+embedding into existing documentation, while JSON is useful for further
+processing of the data.
+
+Translator credits
+------------------
+
+Generates document usable for crediting translators - sorted by language
+and listing all contributors to given language:
+
+.. code-block:: rst
+
+    * Czech
+
+        * Michal Čihař <michal@cihar.com>
+
+    * Dutch
+
+        * Dieter Adriaenssens <dieter.adriaenssens@gmail.com>
+
+
+And it will get rendered as:
+
+    * Czech
+
+        * Michal Čihař <michal@cihar.com>
+        * Weblate Admin <admin@example.com>
+
+    * Dutch
+
+        * Weblate Admin <admin@example.com>
+
+
+Contributor stats
+-----------------
+
+Generates number of words and units translated by translators:
+
+.. code-block:: rst
+
+    ======================================== ======================================== ========== ==========
+    Name                                     Email                                    Words      Count     
+    ======================================== ======================================== ========== ==========
+    Michal Čihař                             michal@cihar.com                               2332        421 
+    Weblate Admin                            admin@example.com                                25          8 
+    ======================================== ======================================== ========== ==========
+
+And it will get rendered as:
+
+    ======================================== ======================================== ========== ==========
+    Name                                     Email                                    Words      Count     
+    ======================================== ======================================== ========== ==========
+    Michal Čihař                             michal@cihar.com                               2332        421 
+    Weblate Admin                            admin@example.com                                25          8 
+    ======================================== ======================================== ========== ==========