Added merge strategy explanation

[bereng]

What is the issue

We need to document the merge strategy we follow for CC development.

What does this PR fix and why was it fixed

Kick starts documentation on the matter which we build upon later on.

[github-actions]

Checklist before you submit for review

• This PR adheres to the Definition of Done
• Make sure there is a PR in the CNDB project updating the Converged Cassandra version
• Use NoSpamLogger for log lines that may appear frequently in the logs
• Verify test results on Butler
• Test coverage for new/modified code is > 80%
• Proper code formatting
• Proper title for each commit staring with the project-issue number, like CNDB-1234
• Each commit has a meaningful description
• Each commit is not very long and contains related changes
• Renames, moves and reformatting are in distinct commits
• All new files should contain the DataStax copyright header instead of the Apache License one

[k-rus]

Thank you for starting explicitly describing the current practice. I have a number of comments to make few points more clear.

[djatnieks]

A few suggestions, but I think this is a good overview - thanks for putting it together.

Maybe a nitpick, but there should be a CNDB ticket for all of our changes, and the PR (and maybe commit comment) should include the ticket number, I believe.

[bereng]

Thanks @djatnieks reading your comment I see I don't want to duplicate the PR checklist here. Which triggered me to realize I should have titled my section 'Merging' instead of 'Contributing'. Wdyt?

[djatnieks]

Looks good, thanks for doing this!

[k-rus]

I am confused with current step formulations, see my comment.

Do this instructions suggest that any commit to main should be cherry-picked to main-5.0.

Or is the purpose of this document to explain how to merge commits from main to main-5.0?

[k-rus]

LGTM, we will iterate on the instructions when necessary.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

❌ Build ds-cassandra-pr-gate/PR-2233 rejected by Butler

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4 regressions found
See build details here

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Found 4 new test failures

Test	Explanation	Runs	Upstream
o.a.c.index.sai.cql.VectorCompaction100dTest.testOneToManyCompaction[eb false]	REGRESSION	🔴⚪	0 / 15
o.a.c.index.sai.cql.VectorKeyRestrictedOnPartitionTest.partitionRestrictedWidePartitionBqCompressedTest[ec false] (compression)	NEW	🔵🔴	0 / 15
o.a.c.index.sai.cql.VectorSiftSmallTest.testMultiSegmentBuild[db false]	NEW	🔴⚪	0 / 15
o.a.c.net.ConnectionTest.testTimeout	REGRESSION	🔴⚪	1 / 15

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Found 6 known test failures

[bereng]

Thx all for the review.