Add supporting themes required for Lotusdocs

themes/hugo-mod-bootstrap-scss/go.mod

@@ -0,0 +1,8 @@
+module github.com/gohugoio/hugo-mod-bootstrap-scss/v5
+
+go 1.16
+
+require (
+	github.com/gohugoio/hugo-mod-jslibs-dist/popperjs/v2 v2.21100.20000 // indirect
+	github.com/twbs/bootstrap v5.3.3+incompatible // indirect
+)