General Improvements: Onboarding concerns causing a barrier to use

Hello; I'm eager to see Beacon reach production, especially the page builder and `beacon_live_admin` codebases. I'm a couple days in on launching beacon in my sample app, and there seem to be a number of rough edges to be addressed. Here are some issues I see, in no special order:

* Can you share how to change the `beacon_live_data` assigns and how you recommend using this, please?
* I uploaded an image to the media library through the `live_admin` app, and there is no clue regarding which URL path to access the media on.
* The `custom` page seems less than useful.


* I'm unsure how I ended up with three sample home pages, maybe I ran `mix setup` too much? Regardless, there needs to be a clear means of erasing any layout or page.


* Please also describe the purpose of `Meta Tags` and each page's `Schema`.
* The sample home page renders `my_component`. This is clearly added through the database seeds, though there is no means of seeing or changing components through `beacon_live_admin` or the `beacon_admin "/admin"` route.

So, six areas where small changes or guidance could really help more people begin using beacon during this preproduction phase. I hope to keep sharing small issues I see, so I can begin to learn how to help during the release process.

Since I'm only a beginner in Elixir and Phoenix, I'm really glad for all the code and resources Dockyard has shared in this space. Seems like a breath of fresh air to say goodbye to Rails, and hello to broader horizons.

Start by reviewing the `beacon_live_admin` and `beacon_admin "/admin"` entry points, the `mix setup` flow, and the database seeds. Break the six concerns into separately testable tasks: document assigns, media URLs, Meta Tags and Schema, and clarify or expose page, layout, and component management. The issue is complete only when each requested behavior or explanation has a clear outcome.

Written by the indexing model from the issue text.