[i18n] Docs section ordering fix

[chalin]

• Contributes to Improved i18n support #4467
• Fixes the order of zh top-level sections
  • Fixes [i18n] Docs section weights need to be adjusted to work with all languages #4572 -- see screenshots below
• Redistributes the weights of the top-level docs sections, without changing the order of en pages.
  Here's proof that the order of pages under en hasn't changed:

  $ (cd public && git diff -bw --ignore-blank-lines) | grep ^diff | grep -v zh
  diff --git a/_redirects b/_redirects
  diff --git a/en/sitemap.xml b/en/sitemap.xml
  diff --git a/site/index.html b/site/index.html

Preview:

• https://deploy-preview-4573--opentelemetry.netlify.app/docs
• https://deploy-preview-4573--opentelemetry.netlify.app/zh/docs/

Screenshots

Before	After

[windsonsea]

Thanks