feat(/calendar): setup alias

<!-- 👋 Hi, thanks for sending a PR to boston-ts-website! 💖. Please fill out all fields below and make sure each item is true and [x] checked. Otherwise we may not be able to review your PR. --> ## PR Checklist - [x] Steps in [CONTRIBUTING.md](https://github.com/SquiggleTools/boston-ts-website/blob/main/.github/CONTRIBUTING.md) were taken ## Overview Adds /calendar alias to go to our official Google calendar. <!-- Description of what is changed and how the code change does that. --> 🐢