Add translation keys for welcome page (#1499)

* Begin Work

* WIP

* Add long title key

* Finish work (for now)

* Fix lint error

* Add continue button key

* Make continue button key generic

locales/en-US/index.json

@@ -1,7 +1,25 @@
 {
+  "auth.welcome.checkbox.subscribe": {
+    "message": "Subscribe to updates about Modrinth"
+  },
+  "auth.welcome.description": {
+    "message": "Thank you for creating an account. You can now follow and create projects, receive updates about your favorite projects, and more!"
+  },
+  "auth.welcome.label.tos": {
+    "message": "By creating an account, you have agreed to Modrinth's <terms-link>Terms</terms-link> and <privacy-policy-link>Privacy Policy</privacy-policy-link>."
+  },
+  "auth.welcome.long-title": {
+    "message": "Welcome to Modrinth!"
+  },
+  "auth.welcome.title": {
+    "message": "Welcome"
+  },
   "button.cancel": {
     "message": "Cancel"
   },
+  "button.continue": {
+    "message": "Continue"
+  },
   "button.edit": {
     "message": "Edit"
   },