Add page on how to build the documentation

Closes PYADAPT-97.

docs/source/documentation.rst

@@ -0,0 +1,13 @@
+Building the documentation
+=========================
+
+This documentation uses `Sphinx <https://www.sphinx-doc.org/>`_
+
+It can be built in different formats.
+
+Run ``cd docs; make`` to see the possible formats.
+
+Run ``cd docs; make html`` to build the documentation in HTML format.
+
+You can see the generated HTML documentation in a browser opening the directory
+`docs/build/html`.

docs/source/index.rst

@@ -12,6 +12,7 @@ Welcome to pEpPythonAdapter's documentation!
 
    install
    testing
+   documentation
    software_using
    api/pEp