tutorial -> documentation in doc/index; add section to /citing, typo fix

content/citing.txt

-Citing kwant
+Citing Kwant
 ============
 
 We provide Kwant as free software under a `BSD license </license.html>`_ as a
-service to the physics community.  If you have used Kwant for work that has lead
-to a scientific publication, please mention this explicitly in the text body.
-In addition, we ask you to cite the main paper that introduces Kwant:
+service to the physics community.  If you have used Kwant for work that has
+lead to a scientific publication, please mention the fact that you used it
+explicitly in the text body.  In addition, we ask you to cite the main paper
+that introduces Kwant:
 
   The reference will be provided here once it is available (soon).
 
+Other references we ask you to consider
+---------------------------------------
+
 If you have profited from the quantum transport functionality of Kwant, please
 also cite the upcoming paper that describes the relevant algorithms. The
 reference will also be added here once it is available.

content/doc/index.txt

 Kwant documentation
 ===================
 
-The two available resources for learning Kwant are its tutorial, and the paper
-inctroducing Kwant structure and design. The tutorial is hands-on, and mainly
-explains how to use Kwant and its various features. The paper on the other
-hand presents a more general perspective, that is useful to kwow for extending
-Kwant functionality.
+The two available resources for learning Kwant are its documentation, and the
+paper inctroducing Kwant structure and design. The documentation contains
+tutorial and package reference. The tutorial part of the documentation is
+hands-on, and mainly explains how to use Kwant and its various features. The
+package reference provides detailed description of every Kwant
+component. Finally, the paper presents a more general
+perspective, that is useful to kwow for extending Kwant functionality.
 
-Kwant tutorial:
+Kwant documentation:
 
 * `browse online </doc/1.0>`_
 * `download pdf <http://downloads.kwant-project.org/doc/kwant-doc-1.0.0.pdf>`_