feat: add a few lance examples in Rust (#3817)

* Add an example on how to write and read dataset
    * Rewrite the Python llm_dataset_creation example in Rust
    * Add an example on how to build hnsw index with Lance dataset
    * It also fixes few typos and missing includes in the Python example
    * Re-structure the example docs section
    

It's linked to the existing example
[section](https://lancedb.github.io/lancedb/examples/examples_rust/) and
restructured the example files.


<img width="745" alt="image"
src="https://github.com/user-attachments/assets/86ca2427-1734-4986-89fd-7a2b936005de"
/>

Author: HaochengLIU

.github/workflows/rust.yml

@@ -58,7 +58,7 @@ jobs:
           echo "ALL_FEATURES=${ALL_FEATURES}" >> $GITHUB_ENV
       - uses: auguwu/clippy-action@1.4.0
         with:
-          check-args: --locked --features ${{ env.ALL_FEATURES }} --tests --benches
+          check-args: --locked --features ${{ env.ALL_FEATURES }} --tests --benches --examples
           token: ${{secrets.GITHUB_TOKEN}}
           deny: warnings
   cargo-deny: