Add a grid of links to the landing page (#1314)

* Split development and documentation requirements

* Add sphinx-copybutton and sphinx-design

* IPython

* Cache

* Add landing page grid

* Minor re-phrasing of landing page

* Add quick links to landing page

Documentation/index.rst

@@ -10,7 +10,12 @@ Econ-ARK documentation -- HARK
    Guides <guides/index>
 
 
-Heterogenous Agents Resources & toolKit (HARK)
+**Useful links**:
+:doc:`Install HARK <guides/installation>` |
+`Source Repository <https://github.com/Econ-ARK/HARK>`__ |
+`Issues & Ideas <https://github.com/Econ-ARK/HARK/issues>`__
+
+**HARK**, the *Heterogenous Agents Resources & toolKit*,
 is a toolkit for the structural modeling of economic choices
 of optimizing and non-optimizing heterogeneous agents.
 
@@ -20,6 +25,90 @@ It is aimed at computational researchers and other
 software developers who are building new models with HARK,
 or are contributing to the core software.
 
-If you are a student trying to learn economics concepts,
+If you are a student trying to learn economic concepts,
 you might want to look at the `DemARK
 <https://github.com/econ-ark/DemARK/>`_ project.
+
+.. grid:: 2
+
+   .. grid-item-card::
+      :padding: 2
+      :text-align: center
+
+      **Quick-start guide**
+      ^^^^^^^^^^^^^^^^^^^^^
+
+      To get up-and-running with HARK, see the quick-start guide
+      for a brief overview
+      and guidance on further resources.
+
+      +++
+
+      .. button-ref:: guides/quick_start
+         :ref-type: doc
+         :color: info
+         :click-parent:
+         :expand:
+
+         Quick Start Guide
+
+   .. grid-item-card::
+      :padding: 2
+      :text-align: center
+
+      **API reference**
+      ^^^^^^^^^^^^^^^^^
+
+      The reference guide contains a detailed description of the HARK API,
+      and assumes an understanding of HARK's key concepts.
+
+      +++
+
+      .. button-ref:: reference/index
+         :ref-type: doc
+         :color: info
+         :click-parent:
+         :expand:
+
+         Tools & Models Reference Guide
+
+   .. grid-item-card::
+      :padding: 2
+      :text-align: center
+
+      **ARKitecture**
+      ^^^^^^^^^^^^^^^
+
+      For a high-level overview of Econ-ARK's structure and design, see the ARKitecture.
+
+      +++
+
+      .. button-ref:: overview/ARKitecture
+         :ref-type: doc
+         :color: info
+         :click-parent:
+         :expand:
+
+         The ARKitecture
+
+   .. grid-item-card::
+      :padding: 2
+      :text-align: center
+
+      **Developer's guide**
+      ^^^^^^^^^^^^^^^^^^^^^
+
+      Saw a typo in the documentation?
+      Want to improve existing functionalities?
+      The contributing guidelines will guide you through
+      the process of improving Econ-ARK.
+
+      +++
+
+      .. button-ref:: guides/contributing
+         :ref-type: doc
+         :color: info
+         :click-parent:
+         :expand:
+
+         Contributing Guide