release 0.5.0 (#536)

* release 0.5.0

Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>

CHANGELOG.md

@@ -1,4 +1,6 @@
 ## master / unreleased
+
+## 0.5.0
  - [FEATURE] Time-ovelapping blocks are now allowed. [#370](https://github.com/prometheus/tsdb/pull/370)
    - Disabled by default and can be enabled via `AllowOverlappingBlock` option.
    - Added `MergeChunks` function in `chunkenc/xor.go` to merge 2 time-overlapping chunks.
@@ -9,8 +11,9 @@
     - Added to remove some code duplication.
  - [ENHANCEMENT] When closing the db any running compaction will be cancelled so it doesn't block.
    - `NewLeveledCompactor` takes a context.
- - [CHANGE] `prometheus_tsdb_storage_blocks_bytes_total` is now `prometheus_tsdb_storage_blocks_bytes`
-
+ - [CHANGE] `prometheus_tsdb_storage_blocks_bytes_total` is now `prometheus_tsdb_storage_blocks_bytes`.
+ - [BUGFIX] Improved Postings Merge performance. Fixes a regression from the the previous release.
+ - [BUGFIX] LiveReader can get into an infinite loop on corrupt WALs.
 
 ## 0.4.0
  - [CHANGE] New `WALSegmentSize` option to override the `DefaultOptions.WALSegmentSize`. Added to allow using smaller wal files. For example using tmpfs on a RPI to minimise the SD card wear out from the constant WAL writes. As part of this change the `DefaultOptions.WALSegmentSize` constant was also exposed.