Add mike (#1264)

* check return types

* set site url

* change docs publish to tag, for now comment it out

mkdocs.yml

@@ -1,4 +1,5 @@
 site_name: ormar
+site_url: 'https://collerek.github.io/ormar/'
 site_description: A simple async ORM with fastapi in mind and pydantic validation.
 nav:
   - Overview: index.md
@@ -77,6 +78,10 @@ markdown_extensions:
   - pymdownx.highlight:
       linenums: true
 plugins:
+- mike:
+    alias_type: symlink
+    canonical_version: latest
+    version_selector: true
 - search
 - gen-files:
     scripts: