docs: concepts and building_applications migration (#3534)

# What does this PR do?

- Migrates the remaining documentation sections to the new documentation format

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## Test Plan

- Partial migration

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docs/docs/distributions/list_of_distributions.mdx

@@ -0,0 +1,134 @@
+---
+title: Available Distributions
+description: List of available distributions for Llama Stack
+sidebar_label: Available Distributions
+sidebar_position: 2
+---
+
+# Available Distributions
+
+Llama Stack provides several pre-configured distributions to help you get started quickly. Choose the distribution that best fits your hardware and use case.
+
+## Quick Reference
+
+| Distribution | Use Case | Hardware Requirements | Provider |
+|--------------|----------|----------------------|----------|
+| `distribution-starter` | General purpose, prototyping | Any (CPU/GPU) | Ollama, Remote APIs |
+| `distribution-meta-reference-gpu` | High-performance inference | GPU required | Local GPU inference |
+| Remote-hosted | Production, managed service | None | Partner providers |
+| iOS/Android SDK | Mobile applications | Mobile device | On-device inference |
+
+## Choose Your Distribution
+
+### 🚀 Getting Started (Recommended for Beginners)
+
+**Use `distribution-starter` if you want to:**
+- Prototype quickly without GPU requirements
+- Use remote inference providers (Fireworks, Together, vLLM etc.)
+- Run locally with Ollama for development
+
+```bash
+docker pull llama-stack/distribution-starter
+```
+
+**Guides:** [Starter Distribution Guide](self_hosted_distro/starter)
+
+### 🖥️ Self-Hosted with GPU
+
+**Use `distribution-meta-reference-gpu` if you:**
+- Have access to GPU hardware
+- Want maximum performance and control
+- Need to run inference locally
+
+```bash
+docker pull llama-stack/distribution-meta-reference-gpu
+```
+
+**Guides:** [Meta Reference GPU Guide](self_hosted_distro/meta-reference-gpu)
+
+### 🖥️ Self-Hosted with NVIDA NeMo Microservices
+
+**Use `nvidia` if you:**
+- Want to use Llama Stack with NVIDIA NeMo Microservices
+
+**Guides:** [NVIDIA Distribution Guide](self_hosted_distro/nvidia)
+
+### ☁️ Managed Hosting
+
+**Use remote-hosted endpoints if you:**
+- Don't want to manage infrastructure
+- Need production-ready reliability
+- Prefer managed services
+
+**Partners:** [Fireworks.ai](https://fireworks.ai) and [Together.xyz](https://together.xyz)
+
+**Guides:** [Remote-Hosted Endpoints](remote_hosted_distro/index)
+
+### 📱 Mobile Development
+
+**Use mobile SDKs if you:**
+- Are building iOS or Android applications
+- Need on-device inference capabilities
+- Want offline functionality
+
+- [iOS SDK](ondevice_distro/ios_sdk)
+- [Android SDK](ondevice_distro/android_sdk)
+
+### 🔧 Custom Solutions
+
+**Build your own distribution if:**
+- None of the above fit your specific needs
+- You need custom configurations
+- You want to optimize for your specific use case
+
+**Guides:** [Building Custom Distributions](building_distro.md)
+
+## Detailed Documentation
+
+### Self-Hosted Distributions
+
+```{toctree}
+:maxdepth: 1
+
+self_hosted_distro/starter
+self_hosted_distro/meta-reference-gpu
+```
+
+### Remote-Hosted Solutions
+
+```{toctree}
+:maxdepth: 1
+
+remote_hosted_distro/index
+```
+
+### Mobile SDKs
+
+```{toctree}
+:maxdepth: 1
+
+ondevice_distro/ios_sdk
+ondevice_distro/android_sdk
+```
+
+## Decision Flow
+
+```mermaid
+graph TD
+    A[What's your use case?] --> B{Need mobile app?}
+    B -->|Yes| C[Use Mobile SDKs]
+    B -->|No| D{Have GPU hardware?}
+    D -->|Yes| E[Use Meta Reference GPU]
+    D -->|No| F{Want managed hosting?}
+    F -->|Yes| G[Use Remote-Hosted]
+    F -->|No| H[Use Starter Distribution]
+```
+
+## Next Steps
+
+1. **Choose your distribution** from the options above
+2. **Follow the setup guide** for your selected distribution
+3. **Configure your providers** with API keys or local models
+4. **Start building** with Llama Stack!
+
+For help choosing or troubleshooting, check our [Getting Started Guide](../getting_started/index.md) or [Community Support](https://github.com/llama-stack/llama-stack/discussions).