Update HISTORY.md for the upcoming 7.6 release (#10543)

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/10543

Reviewed By: anand1976

Differential Revision: D38877168

Pulled By: gitbw95

fbshipit-source-id: d6888f7dbb1f2a5bef144ad2443429a61663c1e8

HISTORY.md

@@ -1,5 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
+
+## 7.6.0 (08/19/2022)
 ### New Features
 * Added `prepopulate_blob_cache` to ColumnFamilyOptions. If enabled, prepopulate warm/hot blobs which are already in memory into blob cache at the time of flush. On a flush, the blob that is in memory (in memtables) get flushed to the device. If using Direct IO, additional IO is incurred to read this blob back into memory again, which is avoided by enabling this option. This further helps if the workload exhibits high temporal locality, where most of the reads go to recently written data. This also helps in case of the remote file system since it involves network traffic and higher latencies.
 * Support using secondary cache with the blob cache. When creating a blob cache, the user can set a secondary blob cache by configuring `secondary_cache` in LRUCacheOptions.