docs: Include toc in sidebar.

Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>

docs/conf.py

diff --git a/docs/conf.py b/docs/conf.py
index 7bcac17..36ba1bb 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -166,6 +166,7 @@
     'repo_name': 'google/skywater-pdk',
 
     'globaltoc_depth': 4,
+    'globaltoc_collapse': False,
 
     # Hide the symbiflow links
     'hide_symbiflow_links': True,