[docs] Move DreamBooth training materials to docs (huggingface#2547)

* move dbooth github stuff to docs

* add notebooks

* 🖍 minor shuffle

* 🖍 fix markdown table

* 🖍 apply feedback

* ✨ make style

* 🖍 minor fix in code snippet

Author: stevhliu

docs/source/en/_toctree.yml

@@ -82,7 +82,7 @@
   - local: training/text_inversion
     title: Textual Inversion
   - local: training/dreambooth
-    title: Dreambooth
+    title: DreamBooth
   - local: training/text2image
     title: Text-to-image
   - local: training/lora