add mkdocs docstring dependency

Author: bradh11

.github/workflows/ci.yml

@@ -1,8 +1,8 @@
-name: ci 
+name: ci
 on:
   push:
     branches:
-      - master 
+      - master
       - main
 jobs:
   deploy:
@@ -12,5 +12,6 @@ jobs:
       - uses: actions/setup-python@v2
         with:
           python-version: 3.x
-      - run: pip install mkdocs-material 
+      - run: pip install mkdocs-material
+      - run: pip install mkdocstrings
       - run: mkdocs gh-deploy --force