[WAF] Update fields for custom detection locations (#18012)

Author: pedrosousa

src/content/docs/waf/detections/leaked-credentials/index.mdx

@@ -72,7 +72,10 @@ Expressions used to specify custom detection locations can include the following
 
 - Fields:
   - [`http.request.body.form`](/ruleset-engine/rules-language/fields/http-request-body/#httprequestbodyform)
+  - [`http.request.body.multipart`](/ruleset-engine/rules-language/fields/http-request-body/#httprequestbodymultipart)
   - [`http.request.body.raw`](/ruleset-engine/rules-language/fields/http-request-body/#httprequestbodyraw)
+  - [`http.request.headers`](/ruleset-engine/rules-language/fields/http-request-header/#httprequestheaders)
+  - [`http.request.uri.query`](/ruleset-engine/rules-language/fields/standard-fields/#httprequesturiquery)
 - Functions:
   - [`lookup_json_string()`](/ruleset-engine/rules-language/functions/#lookup_json_string)
   - [`url_decode()`](/ruleset-engine/rules-language/functions/#url_decode)