Add Gujarati as new language for React doc (#263)

* Add Gujarati as new language for React doc

Sorry , I don't have have direct experience to contribute to translation yet but I have started contributing to old react dev doc:
stale-reactjs-org-translations/gu.reactjs.org#1
stale-reactjs-org-translations/gu.reactjs.org#6

But other than translation, I also made contribution to redux doc: reduxjs/react-redux#1655
And also made some suggestion that might be helpful to write new react doc :https://twitter.com/Harshil__parmar/status/1578469780092485633?s=20
I hope these might help to evaluate me.

* Delete Gu.json

* Added Gujarati as language

langs/langs.json

@@ -9,6 +9,7 @@
   { "code": "fr", "name": "Français", "enName": "French" },
   { "code": "he", "name": "עברית", "enName": "Hebrew" },
   { "code": "hi", "name": "हिन्दी", "enName": "Hindi" },
+  { "code": "gu", "name": "ગુજરાતી", "enName": "Gujarati" },
   { "code": "hu", "name": "magyar", "enName": "Hungarian" },
   { "code": "id", "name": "Bahasa Indonesia", "enName": "Indonesian" },
   { "code": "it", "name": "Italiano", "enName": "Italian" },