Update README & UI screenshots (#14763)

* Refresh README content

* Formatting cleanup

* Add badge links

* More cleanup

* Update getting started section

* Add reference architecture diagram

* Add intro docs link

* Rearrange & expand text

* More restructuring

* Update screenshots

* Tweak image widths

* Tweak screenshots

* Add NetBox Cloud logo

* Fix wrapping

* Add titles for screenshots

* Jumping through more formatting hoops

* Final cleanup

* Add links for plugin resources

docs/index.md

@@ -4,7 +4,7 @@
 
 NetBox is the leading solution for modeling and documenting modern networks. By combining the traditional disciplines of IP address management (IPAM) and datacenter infrastructure management (DCIM) with powerful APIs and extensions, NetBox provides the ideal "source of truth" to power network automation. Read on to discover why thousands of organizations worldwide put NetBox at the heart of their infrastructure.
 
-[![NetBox UI](./media/screenshots/netbox-ui.png)](./media/screenshots/netbox-ui.png)
+[![NetBox UI](./media/screenshots/home-light.png)](./media/screenshots/home-light.png)
 
 ## :material-server-network: Built for Networks