Bug 29183: (follow-up) Add x-koha-query option

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

api/v1/swagger/swagger.yaml

@@ -50,8 +50,12 @@ info:
 
     ## Filtering responses
 
-    The API allows for some advanced response filtering using a json based query syntax that
-    can be added as a query parameter, `q=` or in the request body.
+    The API allows for some advanced response filtering using a JSON based query syntax. The
+    query can be added to the requests:
+
+    * as a query parameter `q=`
+    * in the request body
+    * in a special header `x-koha-query`
 
     For simple field equality matches we can use `{ "fieldname": "value" }` where the fieldname
     matches one of the fields as described in the particular endpoints response object.