Feature/578 prettier.io formatting (#585)

* Reformatted codebase using prettier.io (should not change functional behavior)
* Formatted README.md, added CONTRIBUTING.md, .prettierrc configuration file, and installed pre-commit hook

CONTRIBUTING.md

@@ -0,0 +1,85 @@
+# Contributing
+
+Video Speed Controller is an open source project licensed under the MIT license
+with many contributers. Contributions are welcome, and greatly appreciated.
+
+If you would like to help, getting started is easy.
+
+## Get Started
+
+1. You must have a github account and be logged in
+2. Fork the repo by clicking the "Fork" link on the top-right corner of the page
+3. Once the fork is ready, clone to your local PC
+
+   ```sh
+   $ git clone https://github.com/<USERNAME>/videospeed.git
+   Cloning into 'videospeed'...
+    remote: Enumerating objects: 10, done.
+    remote: Counting objects: 100% (10/10), done.
+    remote: Compressing objects: 100% (9/9), done.
+    remote: Total 877 (delta 3), reused 2 (delta 1), pack-reused 867
+    Receiving objects: 100% (877/877), 317.65 KiB | 2.17 MiB/s, done.
+    Resolving deltas: 100% (543/543), done.
+   ```
+
+4. Create a branch for your changes
+
+   ```sh
+    $ cd videospeed
+    videospeed$ git checkout -b bugfix/1-fix-double-click
+    M   .github/workflows/chrome-store-upload.yaml
+    M   README.md
+    M   options.js
+    Switched to a new branch 'bugfix/1-fix-double-click'
+    videospeed$
+   ```
+
+5. Open the code in your favorite code editor, make your changes
+
+   ```sh
+   echo "Awesome changes" > somefile.js
+   git add .
+   ```
+
+   > Important: Your commit must be formatted using
+   > [prettier](https://prettier.io/). If it is not it may be autoformatted for
+   > you or your pull request may be rejected.
+
+6. Next, open Chrome/Brave/Chromium and enable developer mode via
+   `Settings > Extensions > Manage Extensions` and toggle `Developer mode` in
+   the top-right corner.
+7. Click `Load unpacked` and browse to the folder you cloned videospeed to.
+8. Try out your changes, make sure they work as expected
+9. Commit and push your changes to github
+
+   ```sh
+   git commit -m "Awesome description of some awesome changes."
+   git push
+   ```
+
+10. Open your branch up on the github website then click `New pull request` and
+    write up a description of your changes.
+
+## Optional
+
+### Run Pre-Commit Checks Locally
+
+Installing [pre-commit](https://pre-commit.com/) is easy to do (click the link
+for instructions on your platform). This repo comes with pre-commit already
+configured. Doing this will ensure that your project is properly formatted and
+runs some very basic tests. Once you have pre-commit installed on your system,
+simply enter `pre-commit install` in your terminal in the folder to have these
+checks run automatically each time you commit.
+
+Even better, after issueing the install command you can now manually run
+pre-commit checks before committing via `pre-commit run --all-files`
+
+### Pull Upstream Changes
+
+You should always be working with the latest version of the tool to make pull
+requests easy. If you want to do this easily, just add a second remote to your
+local git repo like this
+`git push --set-upstream origin feature/578-prettier.io-formatting`
+
+Now any time you like to pull the latest version in to your local branch you can
+simply issue the command `git pull upstream master`