Cut v2.19.1 (#7417)

Signed-off-by: NGanesh Vernekar <cs15btech11018@iith.ac.in>

CHANGELOG.md

+## 2.19.1 / 2020-06-18
+
+* [BUGFIX] TSDB: Fix m-map file truncation leading to unsequential files. #7414
+
 ## 2.19.0 / 2020-06-09
 
 * [FEATURE] TSDB: Memory-map full chunks of Head (in-memory) block from disk. This reduces memory footprint and makes restarts faster. #6679

VERSION

-2.19.0
+2.19.1