Hey folks — the new site is awesome!
I noticed the ordering of files in PRs felt off; so I thought on why I found Github's alphabetical sort useful, and I decided to offer this PR to provide even more convenience!
When the source branch adds or changes .changeset/*.md files (eg. from changesets or knope), the compose form now takes its title and body from them, rather than from the top commit.
A single changeset gives its first line as the title and the rest as the body. Several changesets leave the title blank and list each one under a heading made from its first line.
The changesets come from listing .changeset/ at the source head and keeping the entries whose last commit is on the branch. The listing runs alongside the commit lookup, and if anything fails the form falls back to the commit message as before.