docs: Update quickstart page to structure things a little more for the novices (#1873)

# What does this PR do?
Another doc enhancement for
https://github.com/meta-llama/llama-stack/issues/1818

Summary of changes:
- `docs/source/distributions/configuration.md`
   - Updated dropdown title to include a more user-friendly description.

- `docs/_static/css/my_theme.css`
   - Added styling for `<h3>` elements to set a normal font weight.

- `docs/source/distributions/starting_llama_stack_server.md`
- Changed section headers from bold text to proper markdown headers
(e.g., `##`).
- Improved descriptions for starting Llama Stack server using different
methods (library, container, conda, Kubernetes).
- Enhanced clarity and structure by converting instructions into
markdown headers and improved formatting.

- `docs/source/getting_started/index.md`
   - Major restructuring of the "Quick Start" guide:
- Added new introductory section for Llama Stack and its capabilities.
- Reorganized steps into clearer subsections with proper markdown
headers.
- Replaced dropdowns with tabbed content for OS-specific instructions.
- Added detailed steps for setting up and running the Llama Stack server
and client.
- Introduced new sections for running basic inference and building
agents.
- Enhanced readability and visual structure with emojis, admonitions,
and examples.

- `docs/source/providers/index.md`
   - Updated the list of LLM inference providers to include "Ollama."
   - Expanded the list of vector databases to include "SQLite-Vec."

Let me know if you need further details!

## Test Plan
Renders locally, included screenshot.

# Documentation

For https://github.com/meta-llama/llama-stack/issues/1818

<img width="1332" alt="Screenshot 2025-04-09 at 11 07 12 AM"
src="https://github.com/user-attachments/assets/c106efb9-076c-4059-a4e0-a30fa738585b"
/>

---------

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

docs/source/providers/index.md

@@ -1,8 +1,8 @@
 # Providers Overview
 
 The goal of Llama Stack is to build an ecosystem where users can easily swap out different implementations for the same API. Examples for these include:
-- LLM inference providers (e.g., Fireworks, Together, AWS Bedrock, Groq, Cerebras, SambaNova, vLLM, etc.),
-- Vector databases (e.g., ChromaDB, Weaviate, Qdrant, Milvus, FAISS, PGVector, etc.),
+- LLM inference providers (e.g., Ollama, Fireworks, Together, AWS Bedrock, Groq, Cerebras, SambaNova, vLLM, etc.),
+- Vector databases (e.g., ChromaDB, Weaviate, Qdrant, Milvus, FAISS, PGVector, SQLite-Vec, etc.),
 - Safety providers (e.g., Meta's Llama Guard, AWS Bedrock Guardrails, etc.)
 
 Providers come in two flavors: