semantic nerfw docs update (#704)

* download dataset docs

* Update semantic_nerfw.md

docs/nerfology/methods/semantic_nerfw.md

@@ -22,10 +22,16 @@ The transient embeddings are still under development. Please stay tuned.
 
 ### Running Model
 
+Download the Friends Dataset
+
+```bash
+ns-download-data --dataset friends
+```
+
 ```bash
 ns-train semantic-nerfw
 ```
 
 This model defaults to using the "friends" dataset from the paper ["The One Where They Reconstructed 3D Humans and Environments in TV Shows"](https://ethanweber.me/sitcoms3D/).
 
-<video src="https://ethanweber.me/sitcoms3D/media/trimmed_from_supplementary/sfm_and_nerf.mp4" width=300></video>
+<video src="https://ethanweber.me/sitcoms3D/media/trimmed_from_supplementary/sfm_and_nerf.mp4" width=300></video>