Update HISTORY.md and version.h for 7.1 release (#9727)

Summary:
As title

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9727

Test Plan: no code change

Reviewed By: ajkr

Differential Revision: D35034541

Pulled By: hx235

fbshipit-source-id: ae839f23db1bdb9e5f787ca653a7685beb2ada68

HISTORY.md

 # Rocksdb Change Log
-## Unreleased
+## 7.1.0 (03/21/2022)
 ### Public API changes
 * Add DB::OpenAndTrimHistory API. This API will open DB and trim data to the timestamp specified by trim_ts (The data with timestamp larger than specified trim bound will be removed). This API should only be used at a timestamp-enabled column families recovery. If the column family doesn't have timestamp enabled, this API won't trim any data on that column family. This API is not compatible with avoid_flush_during_recovery option.
 

include/rocksdb/version.h

@@ -10,7 +10,7 @@
 #include "rocksdb/rocksdb_namespace.h"
 
 #define ROCKSDB_MAJOR 7
-#define ROCKSDB_MINOR 0
+#define ROCKSDB_MINOR 1
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with