Doc Update (#129)

* init update

* Update terminology.rst

* fix the branch to create an index.html, and fix pre-commit issues

* Doc update

* made several changes to the docs after Shuguang's revision

* fixing pre-commit issues

* fixed the reference file to the final prompt config file

* added google analytics

---------

Co-authored-by: Salman Paracha <salmanparacha@MacBook-Pro-261.local>

docs/source/index.rst

@@ -0,0 +1,67 @@
+Welcome to Arch!
+================
+
+.. image:: /_static/img/arch-logo.png
+   :width: 80%
+   :align: center
+
+.. raw:: html
+
+   <div style="text-align: center; font-size: 1.25rem;">
+   <br>
+   <p>Build <strong>fast</strong>, <strong>robust</strong>, and <strong>personalized</strong> GenAI apps</p>
+   </div>
+
+Arch (built by the contributors of `Envoy <https://www.envoyproxy.io/>`_ ) was born out of the belief that:
+
+  *Prompts are nuanced and opaque user requests, which require the same capabilities as traditional HTTP requests including secure handling, intelligent routing, robust observability, and integration with backend (API) systems for personalization - all outside business logic.*
+
+.. tab-set::
+
+  .. tab-item:: Get Started
+
+    .. toctree::
+      :caption: Get Started
+      :titlesonly:
+
+      get_started/overview
+      get_started/intro_to_arch
+      get_started/quickstart
+
+  .. tab-item:: Concepts
+
+    .. toctree::
+      :caption: Concepts
+      :titlesonly:
+
+      concepts/tech_overview/tech_overview
+      concepts/llm_provider
+      concepts/prompt_target
+
+  .. tab-item:: Guides
+
+    .. toctree::
+      :caption: Guides
+      :titlesonly:
+
+      guides/prompt_guard
+      guides/function_calling
+      guides/observability/observability
+
+  .. tab-item:: Build with Arch
+
+    .. toctree::
+      :caption: Build with Arch
+      :titlesonly:
+
+      build_with_arch/agent
+      build_with_arch/rag
+
+  .. tab-item:: Resources
+
+    .. toctree::
+      :caption: Resources
+      :titlesonly:
+
+      resources/configuration_reference
+      resources/error_target