[Doc] Add OceanBase to supported list

[whhe]

Purpose of the pull request

Add OceanBase to supported list in README.

Brief change log

Add OceanBase to supported list in README.

Verify this pull request

Testing is not necessary.

[whhe]

I didn’t add other databases like Oracle, as I'm not clear if the community has other concerns about it.

[codecov-commenter]

Codecov Report

Merging #13700 (5ab2cbb) into dev (30fd43e) will decrease coverage by 0.02%.
The diff coverage is n/a.

❗ Current head 5ab2cbb differs from pull request most recent head ededcd5. Consider uploading reports for the commit ededcd5 to get more accurate results

@@             Coverage Diff              @@
##                dev   #13700      +/-   ##
============================================
- Coverage     39.06%   39.04%   -0.02%     
+ Complexity     4417     4414       -3     
============================================
  Files          1127     1127              
  Lines         42059    42059              
  Branches       4774     4774              
============================================
- Hits          16431    16424       -7     
- Misses        23815    23823       +8     
+ Partials       1813     1812       -1     

Impacted Files	Coverage Δ
...erver/master/processor/queue/TaskEventService.java	75.00% <0.00%> (-5.36%)	⬇️
...org/apache/dolphinscheduler/remote/utils/Host.java	42.55% <0.00%> (-2.13%)	⬇️
...dolphinscheduler/remote/future/ResponseFuture.java	81.96% <0.00%> (-1.64%)	⬇️
...e/dolphinscheduler/remote/NettyRemotingClient.java	51.38% <0.00%> (-1.39%)	⬇️

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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