fix: add missing i18n text in components

* Affects ActionButtonFooter, ChallengeFooter, ClipboardCopy, SubscriptionForm, VideoButton components
* Adds new entries for each json file: buttons.email, buttons.clipboardCopy, challenge.footer.video, challenge.footer.upvoteAnswer
* Available in English and Spanish

docs/src/content/i18n/en.json

@@ -1,8 +1,10 @@
 {
   "page.title.challenge": "Challenge",
   "author.createdBy": "Created by",
+  "buttons.email": "Email subscription",
   "buttons.star": "Give a star",
   "buttons.sponsor": "Sponsor",
+  "buttons.clipboardCopy": "Copied!",
   "challenge.footer.note": "Note",
   "challenge.footer.running": "Start the project by executing:",
   "challenge.footer.start": "The title of your PR must begin with",
@@ -10,8 +12,10 @@
   "challenge.footer.communityAnswers": "Community solutions",
   "challenge.footer.authorAnswer": "Author's solution",
   "challenge.footer.blogPost": "Article",
+  "challenge.footer.video": "Video",
   "challenge.footer.gettingStarted.title": "To complete this challenge, start by reading: ",
   "challenge.footer.gettingStarted.link": "Getting started",
+  "challenge.footer.upvoteAnswer": "You can upvote an answer with a 👍 if you like it",
   "subscription.button": "Subscribe",
   "subscription.email": "username@gmail.com",
   "subscription.note.title": "Notes",