change docs style to indicate use as NOMAD plugin

Author: lukaspie

docs/assets/favicon.png

@@ -29,13 +29,16 @@ theme:
     accent: '#008A67'
   font:
     text: 'Titillium Web'
-  logo: assets/nomad-logo.png
+  logo: assets/nomad-plugin-logo.png
   favicon: assets/favicon.png
   features:
     - navigation.instant
+    - navigation.footer
     - content.code.copy
     - content.code.annotate
   custom_dir: docs/theme
+  icon:
+    repo: fontawesome/brands/github
 
 markdown_extensions:
   - attr_list
@@ -61,7 +64,6 @@ markdown_extensions:
 
 extra:
   generator: false
-  homepage: https://nomad-lab.eu
 
 use_directory_urls: false