docs: Remove datasets.rst and fix llama-stack build commands (#2061)

# Issue
Closes #2073 

# What does this PR do?
- Removes the `datasets.rst` from the list of document urls as it no
longer exists in torchtune. Referenced PR:
https://github.com/pytorch/torchtune/pull/1781

- Added a step to run `uv sync`. Previously, I would get the following
error:

```
➜  llama-stack git:(remove-deprecated-rst) uv venv --python 3.10
source .venv/bin/activate
Using CPython 3.10.13 interpreter at: /usr/bin/python3.10
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate
(llama-stack) ➜  llama-stack git:(remove-deprecated-rst) INFERENCE_MODEL=llama3.2:3b llama stack build --template ollama --image-type venv --run
zsh: llama: command not found...

```

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan

To test: Run through `rag_agent` example in the `detailed_tutorial.md`
file.

[//]: # (## Documentation)

docs/source/getting_started/detailed_tutorial.md

@@ -42,7 +42,7 @@ powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | ie
 Setup your virtual environment.
 
 ```bash
-uv venv --python 3.10
+uv sync --python 3.10
 source .venv/bin/activate
 ```
 ## Step 2:  Run Llama Stack
@@ -445,7 +445,6 @@ from llama_stack_client import LlamaStackClient
 from llama_stack_client import Agent, AgentEventLogger
 from llama_stack_client.types import Document
 import uuid
-from termcolor import cprint
 
 client = LlamaStackClient(base_url="http://localhost:8321")
 
@@ -463,7 +462,6 @@ urls = [
     "memory_optimizations.rst",
     "chat.rst",
     "llama3.rst",
-    "datasets.rst",
     "qat_finetune.rst",
     "lora_finetune.rst",
 ]