Add explanation for the use of special characters in the search bar.

docs/components/custom-apps/web-app/header.md

@@ -21,9 +21,9 @@ The feedback button is integrated to the header on mobile version only. It is al
 
 ## Search bar
 
-The search bar allow a user to perform a multi-word search over dataset catalog. The search is performed over the metadata as well as the data.
+The search bar allow a user to perform a multi-word search over the datasets catalog. The search is performed over the metadata as well as the data.
 
-With the search bar comes an auto-complete functionality. As the user types, but with a debounce time of 500ms a request is made to the elasticsearch service in order to retrieve a maximum of 5 possible completions for the text the user as typed so far. In each of those completions, the part matching the user's text is bolded. Each completion is clickable which will then replace the current text of the search bar and trigger the search action.
+With the search bar comes an auto-complete functionality. As the user types, but with a debounce time of 500ms, a request is made to the elasticsearch service in order to retrieve a maximum of 5 possible completions for the text the user as typed so far. In each of those completions, the part matching the user's text is bolded. Each completion is clickable which will then replace the current text of the search bar and trigger the search action.
 
 In order to trigger a search the user can either type the `Enter` button of its keyboard when the input of the search bar is focused or click the magnifying glass icon.
 
@@ -31,7 +31,18 @@ The trigger of a search will not only perform a request to the elasticsearch ser
 
 When the search bar has a value, it is possible to reset the search by clicking the cross icon.
 
-The search bar supports advenced queries with `+` or `-` characters in order to make sure that both words are present in the result or instead to exclude the results with a particluar word.
+### Special characters
+
+The search bar supports advanced queries and some special characters
+
+* `-` if this character is used in front of a word, it will exclude it from the results.
+
+* `NOT ()`: it has the same use of `-`.
+`-lyon` and `NOT (lyon)` are two different synthax with the same results.
+
+* `AND`: this logical operator is used for strict intersection. It filters the datasets that have the both words
+
+* `OR`: this is used for union. It is the default behavior of the search bar.
 
 ## User button