Ignore absolute URIs when resolving refs

Do not output bogus warnings in the case of links that goes to other
websites.

utils/resolve-refs.test.tsx

@@ -48,4 +48,10 @@ suite("function resolveRefs", () => {
 		resolveRefs(el, "/");
 		assert.deepEqual(el, elFn());
 	});
+
+	test("ignores absolute URIs", () => {
+		const el = <div>Content with <a href="https://example.org/page.html">Link</a></div>;
+		const resEl = resolveRefs(el, "/");
+		assert.equal(el, resEl);
+	});
 });