Update CHANGELOG.md

Please mark all change in change log and use the ticket from JIRA.

# Milvus 0.5.1 (TODO)

## Bug

## Improvement

## Feature

## Task

# Milvus 0.5.0 (TODO)

## Bug

- MS-655 - Upgrade SPTAG

- \#42 - Put union of index_build_device and search resources to gpu_pool

## New Feature

## Feature

- MS-614 - Preload table at startup

- MS-627 - Integrate new index: IVFSQHybrid

- MS-631 - IVFSQ8H Index support

- MS-576 - Scheduler refactor

- MS-592 - Change showtables stream transport to unary

## New Feature

## Feature

- MS-343 - Implement ResourceMgr

- MS-338 - NewAPI: refine code to support CreateIndex

- MS-339 - NewAPI: refine code to support DropIndex

- MS-332 - Set grpc and thrift server run concurrently

- MS-352 - Add hybrid index

## New Feature

## Feature

- MS-180 - Add new mem manager

- MS-195 - Add nlist and use_blas_threshold conf

- MS-137 - Integrate knowhere

- MS-126 - Add more error code

- MS-128 - Change default db path

## New Feature

## Feature

- MS-57 - Implement index load/search pipeline

- MS-56 - Add version information when server is started

- MS-20 - Clean Code Part 1

## New Feature

## Feature

- MS-5 - Implement Auto Archive Feature

- MS-6 - Implement SDK interface part 1