network.html.haml

- Lowercase the "rate limits" part of the section titles in the admin
  network settings page to be consistent with the rest of the
  application settings page.
  e.g. `Files API rate limits` instead of `Files API Rate Limits`
- Pluralize the "rate limits" part of the section titles in the admin
  network settings page,
  e.g. `Users API rate limits` instead of `Users API rate limit`

Changelog: other