feat(doc): clarify additional requirements

examples/gemma3n/README.md

@@ -0,0 +1,19 @@
+# Gemma-3n
+
+## Requirements
+
+In addition to Axolotl's requirements, Gemma-3n requires
+
+```
+pip3 install timm
+```
+
+If you will load audio datasets, please also install
+
+```
+pip3 install librosa
+```
+
+## Usage
+
+See example configs and the [multimodal doc](https://docs.axolotl.ai/docs/multimodal.html).