Yoga Docs: Rename website-next to website (#1613)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1613

So that GitHub links to edit a page point to the right place.

This will fail in OSS build until I switch the directory used by Vercel instance, but I am waiting to do that until ready to land, since that would cause other in progress changes to fail when exported.

Reviewed By: joevilches

Differential Revision: D54837857

.github/workflows/validate-website.yml

@@ -25,7 +25,7 @@ jobs:
 
       - name: Build Website
         run: yarn build
-        working-directory: website-next
+        working-directory: website
 
   typecheck:
     name: Typecheck [Docusaurus]
@@ -39,4 +39,4 @@ jobs:
 
       - name: yarn tsc
         run: yarn tsc
-        working-directory: website-next
+        working-directory: website