Add supporting themes required for Lotusdocs

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

@@ -0,0 +1,11 @@
+var hash = {
+  left: 'right',
+  right: 'left',
+  bottom: 'top',
+  top: 'bottom'
+};
+export default function getOppositePlacement(placement) {
+  return placement.replace(/left|right|bottom|top/g, function (matched) {
+    return hash[matched];
+  });
+}