Documentation improvements: Remove duplicate READMEs, consistent titles

[pamelafox]

Purpose

The Microsoft Learn samples browser now lets us put the YAML inside a comment, so we don't need the duplicate docs anymore. This PR removes them and generally makes the docs more consistent by prefacing each with "RAG chat: ".
This PR also changes the main title to RAG, to match the short title used on other pages.

Does this introduce a breaking change?

When developers merge from main and run the server, azd up, or azd deploy, will this produce an error?
If you're not sure, try it out on an old environment.

[ ] Yes
[X] No

Does this require changes to learn.microsoft.com docs?

This repository is referenced by this tutorial
which includes deployment, settings and usage instructions. If text or screenshot need to change in the tutorial,
check the box below and notify the tutorial author. A Microsoft employee can do this for you if you're an external contributor.

[ ] Yes
[X] No

Type of change

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[X] Documentation content changes
[ ] Other... Please describe:

Code quality checklist

See CONTRIBUTING.md for more details.

N/A

[mattgotteiner]

Can you change the title of this PDF please

[pamelafox]

Suggested change

	"filter": "sourcefile eq '209884Orig1s000RiskR.pdf'",
	"filter": "sourcefile eq 'employee_handbook.pdf'",

[pamelafox]

Suggested change

	"filter": "sourcefile eq '209884Orig1s000RiskR.pdf'",
	"filter": "sourcefile eq 'employee_handbook.pdf'",

[github-actions]

Check Broken URLs

We have automatically detected the following broken URLs in your files. Review and fix the paths to resolve this issue.

Check the file paths and associated broken URLs inside them. For more details, check our Contributing Guide.

File Full Path	Issues
README.md	# Link Line Number 1 https://aka.ms/entgptsearchblog 291 2 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/access-control-in-generative-ai-applications-with-azure/ba-p/3956408 295
docs/deploy_lowcost.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/azure-ai-search-outperforming-vector-search-with-hybrid/ba-p/3929167 43
docs/customization.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/azure-ai-search-outperforming-vector-search-with-hybrid/ba-p/3929167 120
docs/productionizing.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/azure-architecture-blog/azure-openai-landing-zone-reference-architecture/ba-p/3882102 86
docs/deploy_features.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/announcing-the-public-preview-of-integrated-vectorization-in/ba-p/3960809#:~:text=Integrated%20vectorization%20is%20a%20new%20feature%20of%20Azure,pull-indexers%2C%20and%20vectorization%20of%20text%20queries%20through%20vectorizers 209
docs/data_ingestion.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/announcing-the-public-preview-of-integrated-vectorization-in/ba-p/3960809#:~:text=Integrated%20vectorization%20is%20a%20new%20feature%20of%20Azure,pull-indexers%2C%20and%20vectorization%20of%20text%20queries%20through%20vectorizers 78

[pamelafox]

Broken links are due to planned techcommunity upgrade, so those are expected.

[github-actions]

Check Broken URLs

We have automatically detected the following broken URLs in your files. Review and fix the paths to resolve this issue.

Check the file paths and associated broken URLs inside them. For more details, check our Contributing Guide.

File Full Path	Issues
README.md	# Link Line Number 1 https://aka.ms/entgptsearchblog 291 2 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/access-control-in-generative-ai-applications-with-azure/ba-p/3956408 295
docs/deploy_lowcost.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/azure-ai-search-outperforming-vector-search-with-hybrid/ba-p/3929167 43
docs/customization.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/azure-ai-search-outperforming-vector-search-with-hybrid/ba-p/3929167 120
docs/productionizing.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/azure-architecture-blog/azure-openai-landing-zone-reference-architecture/ba-p/3882102 86
docs/deploy_features.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/announcing-the-public-preview-of-integrated-vectorization-in/ba-p/3960809#:~:text=Integrated%20vectorization%20is%20a%20new%20feature%20of%20Azure,pull-indexers%2C%20and%20vectorization%20of%20text%20queries%20through%20vectorizers 209
docs/data_ingestion.md	# Link Line Number 1 https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/announcing-the-public-preview-of-integrated-vectorization-in/ba-p/3960809#:~:text=Integrated%20vectorization%20is%20a%20new%20feature%20of%20Azure,pull-indexers%2C%20and%20vectorization%20of%20text%20queries%20through%20vectorizers 78