Continue chapter 7 notebook migration - restored chapter 7 .rst file

Author: salexanian

docs/_toc.yml

@@ -34,7 +34,10 @@ parts:
     - file: friedland/index.rst
       sections:
       - file: friedland/chapter_6.rst
-      - file: friedland/chapter_7.ipynb
+      - file: friedland/chapter_7.rst
+        title: Chapter 7 - Part I
+      - file: friedland/chapter_7_part_2.ipynb
+        title: Chapter 7 - Part II
       - file: friedland/chapter_9.ipynb
       - file: friedland/chapter_10.ipynb
   - chapters: