Add comment for clusters and UI display

[BlackBear2003]

What's the purpose of this PR

Add comment for clusters and UI display

Which issue(s) this PR fixes:

Fixes ##5067

Brief changelog

it looks like:

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.
• Update the CHANGES log.

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (6657a58) 49.65% compared to head (8db44fa) 49.60%.

Files	Patch %	Lines
...com/ctrip/framework/apollo/biz/entity/Cluster.java	0.00%	4 Missing ⚠️
.../ctrip/framework/apollo/common/dto/ClusterDTO.java	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5072      +/-   ##
============================================
- Coverage     49.65%   49.60%   -0.06%     
+ Complexity     1905     1904       -1     
============================================
  Files           372      372              
  Lines         11558    11564       +6     
  Branches       1127     1127              
============================================
- Hits           5739     5736       -3     
- Misses         5478     5488      +10     
+ Partials        341      340       -1     

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[nobodyiam]

This looks great! Please find some comments below:

1. I think the comment is similar to the remarks of namespace, so it's better to use the same term, e.g. Remarks and 备注
   
   

2. I think the comment should not be mandatory, as it's not a necessary information

3. When displaying the comment, it's not necessary to display the prefix comment:

[BlackBear2003]

I think the comment is similar to the remarks of namespace, so it's better to use the same term, e.g. Remarks and 备注

changed terms at front-end from 'comment' to 'remarks'.

I'm not sure should we change the sql and entity's field name? I see there is comment in AppNamespace, Commit and Item while there is not remarks. So I just use remark when UI display.

[nobodyiam]

This looks fantastic! Below are a few comments for your consideration. Additionally, please update the CHANGES.md file to inform users about this new feature.

[nobodyiam]

LGTM