Add 0.11.0 changelog (#9078)

This release I'm experimenting with a new changelog format that doesn't
sap hours of extra time to put together. Basically:

1. Sort by "development area" instead of added / changed / fixed. These
distinctions are often unclear anyway and we have no automated way of
assigning them currently. "Development area" sorting feels equally
useful (if not more useful). Our changelog generator also already does
"development area" categorization so this is efficient.
2. Sort by "importance" and trim out irrelevant changes. This is
laborious, but I already do this as part of my blog post construction
methodology, so it isn't "extra" work.