Improvements to the doc (#1989)

* Added Overview page

* Revised Getting Started page

* Minor revision

* Edited readme, minor modifications to docs

* Removed sweep.yaml, .devcontainer, .ergomake

* Moved security.md to .github, added contributing.md

* changes as per code review

* updated contributing.md

* fixed broken links & added missing links in doc, improved structure

* fixed link in wsl setup

* fixed server link, added https cloning in yarn-setup

* removed package-lock.json

* added doc card, admonitions

* removed underline from nav buttons

docs/docs/start/overview.mdx

@@ -6,6 +6,8 @@ sidebar_custom_props:
 ---
 import ThemedImage from '@theme/ThemedImage';
 
+
+
 Twenty is an Open Source CRM that provides flexibility, tailored to your business needs. It helps you break free from vendor lock-in and limitations, and provides the tools needed to harness the full potential of your data while ensuring a sleek and effortlessly intuitive design that teams will love to use.  
 <ThemedImage sources={{light: "../img/light-doc-preview.png", dark:"./img/dark-doc-preview.png"}} style={{width:'100%', maxWidth:'800px'}}/>