Add CHANGELOG

This adds a CHANGELOG in the same style as urql's
main CHANGELOG, as we're preparing for a v1.0.0 stable
release.

CHANGELOG.md

@@ -0,0 +1,51 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+If a change is missing an attribution, it may have been made by a Core Contributor.
+
+- Critical bugfixes or breaking changes are marked using a `warning` symbol: ⚠️
+- Significant new features or enhancements are marked using the `sparkles` symbol: ✨
+
+_The format is based on [Keep a Changelog](http://keepachangelog.com/)._
+
+## [v1.0.0-rc.6](https://github.com/FormidableLabs/urql-exchange-graphcache/compare/v1.0.0-rc.5...v1.0.0-rc.6)
+
+- ⚠ Fix concurrency issue where a single operation is reexecuted multiple times (see [#70](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/70))
+- Skip writing `undefined` to the cache and log a warning in development (see [#71](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/71))
+- Allow `query` to be passed as a string to `store.updateQuery` (see [#72](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/72))
+
+## [v1.0.0-rc.5](https://github.com/FormidableLabs/urql-exchange-graphcache/compare/v1.0.0-rc.4...v1.0.0-rc.5)
+
+- ⚠ Fix user-provided `keys` config not being able to return `null` (see [#68](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/68))
+
+## [v1.0.0-rc.4](https://github.com/FormidableLabs/urql-exchange-graphcache/compare/v1.0.0-rc.3...v1.0.0-rc.4)
+
+- ⚠ Fix development warnings throwing an error for root fields (see [#65](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/65))
+
+## [v1.0.0-rc.3](https://github.com/FormidableLabs/urql-exchange-graphcache/compare/v1.0.0-rc.2...v1.0.0-rc.3)
+
+_Note: This is release contains a bug that `v1.0.0-rc.4` fixes_
+
+- Fix warning condition for missing entity keys (see [98287ae](https://github.com/FormidableLabs/urql-exchange-graphcache/commit/98287ae))
+
+## [v1.0.0-rc.2](https://github.com/FormidableLabs/urql-exchange-graphcache/compare/v1.0.0-rc.1...v1.0.0-rc.2)
+
+_Note: This is release contains a bug that `v1.0.0-rc.3` fixes_
+
+- Add warnings for unknown fields based on the schema and deduplicate warnings (see [#63](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/63))
+
+## [v1.0.0-rc.1](https://github.com/FormidableLabs/urql-exchange-graphcache/compare/v1.0.0-rc.0...v1.0.0-rc.1)
+
+This is the first release that adds _schema awareness_. Passing a schema to Graphcache allows it to make deterministic
+assumptions about the cached results it generates from its data. It can deterministically match fragments to interfaces,
+instead of resorting to a heuristic, and it can provide _partial results_ for queries. With a `schema` passed to Graphcache,
+as long as only nullable fields are uncached and missing, it will still provide an initial cached result.
+
+- ✨ Add schema awareness using the `schema` option (see [#58](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/58))
+- ✨ Allow for partial results to cascade missing values upwards (see [#59](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/59))
+- Fix `store.keyOfEntity` not using root names from the schema (see [#62](https://github.com/FormidableLabs/urql-exchange-graphcache/pull/62))
+
+## v1.0.0-rc.0
+
+This is where this CHANGELOG starts.
+For a log on what happened in `beta` and `alpha` releases, please read the commit history.