add NL source for financial information

JSON-guidelines.md

@@ -86,7 +86,8 @@ List of validated sources for financial data:
 * [https://www.infogreffe.fr/](infogreffe.fr) (FR-official);
 * [https://www.bundesanzeiger.de/](bundesanzeiger.de) (DE-official);
 * [https://infocamere.it/](italianbusinessregister.it) (IT);
-* [https://find-and-update.company-information.service.gov.uk/](find-and-update.company-information.service.gov.uk) (UK).
+* [https://find-and-update.company-information.service.gov.uk/](find-and-update.company-information.service.gov.uk) (UK);
+* [https://www.kvk.nl/english/ordering-products-from-the-business-register/kvk-annual-financial-statements/](KVK.nl) (NL).
 
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