docs: add links to useful tolgee docs pages

CONTRIBUTING.md

@@ -128,6 +128,14 @@ To do this:
 
 Using the in-context translation Screenshot feature also requires installing the _Tolgee Tools_ browser extension.
 
+To define new translation keys yourself, contact us on the Discord about getting Edit Keys scope access to the project.
+
+See these documentation pages about how to use Tolgee in code:
+
+- [Using `$t()` and the `T` component](https://tolgee.io/js-sdk/integrations/svelte/translating)
+- [Full spec for `$t()`](https://tolgee.io/js-sdk/api/core_package/tolgee#t)
+- [ICU Message Format](https://tolgee.io/platform/translation_process/icu_message_format)
+
 ### Downloading Translations
 
 This project uses Tolgee to manage translations.