contributing doc

CONTRIBUTING.md

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+Code contributions are welcome! Please commit any pull requests against the `master` branch.
+
+# Localization (l10n)
+
+[![Crowdin](https://d322cqt584bo4o.cloudfront.net/bitwarden-web/localized.svg)](https://crowdin.com/project/bitwarden-web)
+
+We use a translation tool called [Crowdin](https://crowdin.com) to help manage our localization efforts across many different languages.
+
+If you are interested in helping translate the Bitwarden web vault into another language (or make a translation correction), please register an account at Crowdin and join our project here: https://crowdin.com/project/bitwarden-web
+
+If the language that you are interested in translating is not already listed, create a new account on Crowdin, join the project, and contact the project owner (https://crowdin.com/profile/kspearrin).
+
+You can read Crowdin's getting started guide for translators here: https://support.crowdin.com/crowdin-intro/