docs: Move to standard folder naming

I also like docs/ more than doc/, but it's the standard in Qibo, and this is valuable

doc/source/index.rst

@@ -0,0 +1,73 @@
+.. title::
+   QiboTN
+
+What is QiboTN?
+===============
+
+QiboTN  is the dedicated `Qibo <https://github.com/qiboteam/qibo>`_ backend to support large-scale simulation of quantum circuits and acceleration.
+
+Supported Computation:
+
+- Tensornet (TN)
+- Matrix Product States (MPS)
+
+Tensor Network contractions to:
+
+- dense vectors
+- expecation values of given Pauli string
+
+The supported HPC configurations are:
+
+- single-node CPU
+- single-node GPU or GPUs
+- multi-node multi-GPU with Message Passing Interface (MPI)
+- multi-node multi-GPU with NVIDIA Collective Communications Library (NCCL)
+
+Currently, the supported tensor network libraries are:
+
+- [cuQuantum](https://github.com/NVIDIA/cuQuantum), an NVIDIA SDK of optimized libraries and tools for accelerating quantum computing workflows.
+- [quimb](https://quimb.readthedocs.io/en/latest/), an easy but fast python library for ‘quantum information many-body’ calculations, focusing primarily on tensor networks.
+
+How to Use the Documentation
+============================
+
+Welcome to the comprehensive documentation for QiboTN! This guide will help you navigate through the various sections and make the most of the resources available.
+
+
+1. **Getting started**: Begin by referring to the
+   :doc:`/getting-started/installation/` guide to set up the ``QiboTN`` library in your environment.
+
+2. **Tutorials**: Explore the :doc:`getting-started/quickstart/` section for basic usage examples
+
+
+Contents
+--------
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Introduction
+
+   getting-started/index
+
+.. toctree::
+    :maxdepth: 2
+    :caption: Main documentation
+
+    api-reference/modules
+    Developer guides <https://qibo.science/qibo/stable/developer-guides/index.html>
+
+.. toctree::
+    :maxdepth: 1
+    :caption: Documentation links
+
+    Qibo docs <https://qibo.science/qibo/stable/>
+    Qibolab docs <https://qibo.science/qibolab/stable/>
+    Qibocal docs <https://qibo.science/qibocal/stable/>
+    Qibosoq docs <https://qibo.science/qibosoq/stable/>
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`