Add supporting themes required for Lotusdocs

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

@@ -0,0 +1,11 @@
+// @flow
+import type { Placement } from '../enums';
+
+const hash = { left: 'right', right: 'left', bottom: 'top', top: 'bottom' };
+
+export default function getOppositePlacement(placement: Placement): Placement {
+  return (placement.replace(
+    /left|right|bottom|top/g,
+    matched => hash[matched]
+  ): any);
+}