7780a360eb
Summary: Make "unreleased" section for HISTORY.md with things misplaced into 6.12 and 6.13 Pull Request resolved: https://github.com/facebook/rocksdb/pull/7401 Test Plan: see how it goes, and `git diff origin/6.13.fb HISTORY.md` Reviewed By: jay-zhuang Differential Revision: D23759740 Pulled By: pdillinger fbshipit-source-id: fc441916c7ff2bbb8d5384137653b340d4c47674