add CHANGES.md for track.

[JaredTan95]

What's the purpose of this PR

add CHANGES.md for track.

NOTE:
Content needs to be updated in envery PR and after the each version release

Follow this checklist to help us incorporate your contribution quickly and easily:

• Read the Contributing Guide before making this pull request.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit tests to verify the code.
• Run mvn clean test to make sure this pull request doesn't break anything.

[codecov-commenter]

Codecov Report

Merging #3747 (62e64c8) into master (a64ed3e) will decrease coverage by 0.06%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #3747      +/-   ##
============================================
- Coverage     50.39%   50.32%   -0.07%     
+ Complexity     2375     2374       -1     
============================================
  Files           457      457              
  Lines         14435    14435              
  Branches       1457     1457              
============================================
- Hits           7274     7264      -10     
- Misses         6657     6665       +8     
- Partials        504      506       +2     

Impacted Files	Coverage Δ
...mework/apollo/portal/component/PortalSettings.java	57.81% <0.00%> (-7.82%)	⬇️
...ework/apollo/internals/RemoteConfigRepository.java	86.25% <0.00%> (-3.13%)	⬇️

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[nobodyiam]

LGTM