docs: add note about maintenance status (#153)

* Update getting-started.md

* Update README.md

* Apply suggestions from code review

Co-authored-by: Sarah Dayan <sarah.dayan@algolia.com>

Co-authored-by: Sarah Dayan <sarah.dayan@algolia.com>

README.md

@@ -9,6 +9,8 @@
 
 Add fast and relevant search to your Jekyll site.
 
+> While this plugin was created by Algolia, it is not an officially supported API client. It is possible that future major versions of Jekyll break compatibility, or require changes.
+
 ## Usage
 
 ```shell

docs-src/src/getting-started.md

@@ -10,6 +10,8 @@ layout: content-with-menu.pug
 `jekyll-algolia` is a Jekyll plugin that lets you push all your content in an
 Algolia index.
 
+> While this plugin was created by Algolia, it is not an officially supported API client. It is possible that future major versions of Jekyll break compatibility, or require changes.
+
 ## Requirements
 
 You'll need: