Add supporting themes required for Lotusdocs

themes/hugo-mod-jslibs-dist/popperjs/package/lib/utils/getMainAxisFromPlacement.js.flow

@@ -0,0 +1,8 @@
+// @flow
+import type { Placement } from '../enums';
+
+export default function getMainAxisFromPlacement(
+  placement: Placement
+): 'x' | 'y' {
+  return ['top', 'bottom'].indexOf(placement) >= 0 ? 'x' : 'y';
+}