Expand toc nav depth (#296)

* Increase navigation depth to 3

* Expand left sidebar

* Revert "Expand left sidebar"

This reverts commit a3dc19b.

Co-authored-by: “gathoni-k” <“[email protected]”>

Author: remigathoni

src/index.md

@@ -28,7 +28,7 @@ the left sidebar.
 ## Table of Contents
 
 ```{toctree}
-:maxdepth: 2
+:maxdepth: 3
 :numbered:
 
 introduction/index.md