TODO: Add social impact use cases to awesome-ipfs

This is mostly a TODO for myself to submit a future PR with links, but I work on various social impact projects that leverage IPFS and content addressing in useful and interesting ways. I'd love to add a section with links for folks to check out articles and documentation on interesting use cases, and I'm creating this issue to remind myself to do it later in a publicly accountable way.

Start by reviewing the repository's awesome-list structure and existing categories, then identify the appropriate place for a social-impact section. Done means adding a curated section with links to relevant IPFS and content-addressing use cases; the issue names no specific file or test.

Written by the indexing model from the issue text.