Community-page copyedits

[chalin]

• Some of the changes in this PR were inspired by my review of Edits to follow up contribution guidelines work #3846
• hugo.yaml: Tweaks page-footer link titles, which appear as text in the community-list -- see the screenshot below
• Adds a new i18n/en.toml file, with some overrides (to the Docsy defaults) of community-related i18n entries. In particular, I add a link to the new Contributing docs section at the start of the Develop and Contribute community page section.
• This PR may feel like it's a round-about way of making copyedits to the Community page, but that's because we use a Docsy-inspired shortcode to render part of the page content.

Preview: https://deploy-preview-3885--opentelemetry.netlify.app/community/

Screenshot