Fix epochs schema to resolve double nesting of sdpi:Epoch element.#521

PaulMartinsen wants to merge 3 commits intomasterIHE/DEV.SDPi:masterfrom

520-example-13-does-not-comply-to-the-schema-because-of-sdpiepochsIHE/DEV.SDPi:520-example-13-does-not-comply-to-the-schema-because-of-sdpiepochsCopy head branch name to clipboard