copy polymer example from vercel/vercel (#1024)

Author: erikareads

framework-boilerplates/polymer/.gitignore

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+build/
+node_modules/
+.env
+.env.build
+.vercel

framework-boilerplates/polymer/.vercelignore

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+README.md

framework-boilerplates/polymer/README.md

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+![Polymer Logo](https://github.com/vercel/vercel/blob/main/packages/frameworks/logos/polymer.svg)
+
+# Polymer Example
+
+This directory is a brief example of a [Polymer](https://www.polymer-project.org/) app that can be deployed to Vercel with zero configuration.
+
+## Deploy Your Own
+
+Deploy your own Polymer project with Vercel.
+
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https://github.com/vercel/examples/tree/main/framework-boilerplates/polymer&template=polymer)
+
+_Live Example: https://polymer-template.vercel.app_
+
+### How We Created This Example
+
+To get started with Polymer deployed with Vercel, you can use the [Polymer CLI](https://polymer-library.polymer-project.org/3.0/docs/tools/polymer-cli) to initialize the project:
+
+```shell
+$ polymer init
+```