Add mattmazzola/devcontainers to collections-index.yml#569

mattmazzola wants to merge 1 commit intodevcontainers:gh-pagesdevcontainers/devcontainers.github.io:gh-pagesfrom

mattmazzola:mattmazzola/mainmattmazzola/devcontainers.github.io:mattmazzola/mainCopy head branch name to clipboard