add dockerfile which builds a cinny container served by nginx

Dockerfile

@@ -0,0 +1,21 @@
+## Builder
+FROM node:14-alpine as builder
+
+WORKDIR /src
+
+COPY . /src
+RUN npm install \
+  && npm run build
+
+
+## App
+FROM nginx:alpine
+
+COPY --from=builder /src/dist /app
+COPY --from=builder /src/olm.wasm /app/olm.wasm
+
+# Insert wasm type into Nginx mime.types file so they load correctly.
+RUN sed -i '3i\ \ \ \ application/wasm wasm\;' /etc/nginx/mime.types
+
+RUN rm -rf /usr/share/nginx/html \
+  && ln -s /app /usr/share/nginx/html