Edited azure-container-apps/README.md for style and consistency

[Penderworth]

This is a large edit of the entire Azure Container Apps readme file. It now matches the style and flow of other readme files. I tested most of the steps, but will leave comments on items I have outlying questions about.

Other notes:

• We now assume that the reader of this article is here specifically for the Azure Portal method, not the CLI method that we describe in AKB.
• I used a slightly new approach to steps for filling out fields. Instead of an unordered list, which I previously used in AKB, I used a sub-item ordered list to make it clear that people need to fill out all the fields, not just some of them.
• I created a new "get help" section, but that may not be the best title to hold all items in there, so please feel free to suggest another appendix title for some if they should be reorganized.

The TOC doesn't show the full outline with its subheaders, so in case you're wondering what that is:

[Penderworth]

@black-bryan Alrighty, this big edit is ready for your review, and anyone else's who'd like to take a look. Once we get the SA/SE reviews, I'll get one from the tech writing team as well. I'll start work on the DigitalOcean edit after we merge this in case we make style decisions here :)

[black-bryan]

Question: For consistency, can we rename the file to all-caps README instead of CamelCase?

Yes, lets match the naming format for this file name as well.

[Penderworth]

There doesn't seem to be many references in the support site docs to this GitHub repo (I think just the general SCIM bridge deployment article and step 3 of the Azure Containers article? Maybe the scim-update article?). This might already be on your radar, but if not, but might be good to look at some more cross referencing. It's also a bit difficult to find all the information you need just on the support site, since the SCIM bridge docs branch off in a lot of different ways.

@HeatherRobb Indeed, this is rather intentional. We didn't want to over-market the options in this repo because there are a lot of great options in AKB itself, and with SCIM, lower barriers to entry are ideal. I can look into auditing this, though, and see if there are other places we can add scim-examples.