improve RELEASE.md

[longwuyuan]

What this PR does / why we need it:

This PR reorganizes the info and adds details to the RELEASE.md file

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

fixes ##7495

How Has This Been Tested?

Tested while performing releases and discussed with others involved in releases

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

[k8s-ci-robot]

@longwuyuan: This issue is currently awaiting triage.

If Ingress contributors determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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[longwuyuan]

/assign @strongjz

[longwuyuan]

/aread docs

[strongjz]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: longwuyuan, strongjz

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• OWNERS [strongjz]

Approvers can indicate their approval by writing /approve in a comment
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[tao12345666333]

/lgtm