metro v0.86.0 release notes

[Breaking]: Metro now always emits whole-bundle source maps as index maps, and stores each module's map internally as a VlqMap (https://github.com/react/metro/pull/1764, https://github.com/react/metro/pull/1765 by @robhogan). Custom serialisers/transformers must consume/provide VlqMap mappings, not tuples.
[Breaking]: Remove deprecated default exports from public entry points (https://github.com/react/metro/pull/1759 by @robhogan)
[Breaking]: Remove support for deprecated YAML and .es6 config files (https://github.com/react/metro/pull/1752 by @robhogan)
[Breaking]: Remove long-deprecated resolver.blacklistRE config in favour of blockList (https://github.com/react/metro/pull/1758 by @robhogan)
[Fix]: Fix HttpStore write retries incorrectly using the read endpoint's config (https://github.com/react/metro/pull/1751 by @durvesh1992)
[Performance]: Source maps work makes Metro use 50% less memory and serve source maps 2x faster, for faster RNDT loads (https://github.com/react/metro/pull/1741, https://github.com/react/metro/pull/1742, https://github.com/react/metro/pull/1743, https://github.com/react/metro/pull/1760, https://github.com/react/metro/pull/1763, https://github.com/react/metro/pull/1764, https://github.com/react/metro/pull/1765 by @robhogan)

Full Changelog: https://github.com/react/metro/compare/v0.85.0...v0.86.0