text: Title: Avoid documents indexing in search engine (until we allow intentionally publishing pages)
  Body: ## Bug Report
  
  **Problematic behavior**
  
  Some documents are available publicly (without being logged) and may thus end-up being indexed by search engine.
  
  **Expected behavior/code**
  
  We don't want this to happen until we implement the possibility to "publish" a page intentionally.
  
  **Possible Solution**
  
  Documents should be flagged as "noindex".
  
  Add a meta tag in the <head> section of the page (See https://developers.google.com/search/docs/crawling-indexing/block-indexing for more information):
  ```
  <meta name="robots" content="noindex">
  ```
  
  It will have to be removed on published documents when we will allow it.