Update documentation

Author: JanLuca

docs/source/general.rst

@@ -0,0 +1,38 @@
+.. _general:
+
+
+Introduction
+============
+
+variPEPS is a Python tensor network library developed for variational ground
+state simulations in two spatial dimensions applying gradient optimization using
+automatic differentation.
+
+For a detailed report on the method, please see `our open-access publication on
+SciPost (doi:10.21468/SciPostPhysLectNotes.86)
+<https://doi.org/10.21468/SciPostPhysLectNotes.86>`_.
+
+Installation using pip
+======================
+
+The current version of the variPEPS Python package is available on `PyPI
+<https://pypi.org/project/variPEPS/>`_. It can be easily installed using the
+Python package manager pip:
+
+.. code-block:: console
+
+   $ python3 -m pip install variPEPS
+
+Usage
+=====
+
+ToDo
+
+Citation
+========
+
+We are happy if you want to use the framework for your research. To cite our
+work we provide a list of our preferred references on the `GitHub page of the
+project
+<https://github.com/variPEPS/variPEPS_Python?tab=readme-ov-file#citation>`_. Please
+check there for a current list.

docs/source/index.rst

@@ -3,8 +3,9 @@ Variational PEPS
 
 .. toctree::
    :maxdepth: 2
-   :caption: Design
+   :caption: VariPEPS
 
+   general
    design/features
 
 .. toctree::