Exclude alerts: improve documentation (#13046)

Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu>

docs/querying/api.md

@@ -679,7 +679,7 @@ URL query parameters:
 - `rule_name[]=<string>`: only return rules with the given rule name. If the parameter is repeated, rules with any of the provided names are returned. If we've filtered out all the rules of a group, the group is not returned. When the parameter is absent or empty, no filtering is done.
 - `rule_group[]=<string>`: only return rules with the given rule group name. If the parameter is repeated, rules with any of the provided rule group names are returned. When the parameter is absent or empty, no filtering is done.
 - `file[]=<string>`: only return rules with the given filepath. If the parameter is repeated, rules with any of the provided filepaths are returned. When the parameter is absent or empty, no filtering is done.
-- `exclude_alerts`: only return rules without active alerts. When this parameter is absent or empty, no filtering is done.
+- `exclude_alerts=<bool>`: only return rules, do not return active alerts.
 
 ```json
 $ curl http://localhost:9090/api/v1/rules