added know issue for {elastic + ubuntu 16.04} (see #38) + fix typos

README.md

@@ -343,7 +343,7 @@ To create it, please follow these instructions:
 
 - While setting up the database, we'll need to activate two PostgreSQL extensions: [unaccent](https://www.postgresql.org/docs/current/static/unaccent.html) and [trigram](https://www.postgresql.org/docs/current/static/pgtrgm.html).
   This can only be achieved if the user, configured in `config/database.yml`, was granted the _SUPERUSER_ role **OR** if these extensions were white-listed.
-  So here's your choice, mainly depending on your security requirements:
+  So here's your choices, mainly depending on your security requirements:
   - Use the default PostgreSQL super-user (postgres) as the database user of fab-manager.
   - Set your user as _SUPERUSER_; run the following command in `psql` (after replacing `sleede` with you user name):
   
@@ -361,7 +361,7 @@ To create it, please follow these instructions:
   - `app/controllers/api/members_controllers.rb@search` is using `f_unaccent()` (see above) and `regexp_replace()`
 - If you intend to contribute to the project code, you will need to run the test suite with `rake test`.
   This also requires your user to have the _SUPERUSER_ role. 
-  Please see the [known issues](#known-issues) for more informations about this.
+  Please see the [known issues](#known-issues) section for more informations about this.
 
 <a name="elasticsearch"></a>
 ## ElasticSearch
@@ -655,7 +655,15 @@ You can see an example on the [repo of navinum gamification plugin](https://gith
 
         ALTER ROLE sleede WITH SUPERUSER;
 
- DO NOT do this in a production environment, as this would lead to a serious security issue.
+  DO NOT do this in a production environment, unless you know what you're doing: this could lead to a serious security issue.
+
+- With Ubuntu 16.04, ElasticSearch may refuse to start even after having configured the service with systemd. 
+  To solve this issue, you may have to set `START_DAEMON` to `true` in `/etc/default/elasticsearch`.
+  Then reload ElasticSearch with:
+  
+  ```bash
+  sudo systemctl restart elasticsearch.service
+  ```
 
 <a name="related-documentation"></a>
 ## Related Documentation