docs: add v3.3.0 changelog entries

[MSalopek]

Description

Closes: #XXXX

Add changelog file and cleanup entries.

---

Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• included the correct docs: prefix in the PR title
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

I have...

• Confirmed the correct docs: prefix in the PR title
• Confirmed all author checklist items have been addressed
• Confirmed that this PR only changes documentation
• Reviewed content for consistency
• Reviewed content for spelling and grammar
• Tested instructions (if applicable)
• Checked that the documentation website can be built and deployed successfully (run make build-docs)

[mpoke]

The date is enough for a summary. Info on the release should go in the release notes.

[MSalopek]

I added the release highlights, I can remove them but they do no harm.

[mpoke]

I just want to keep things simple and have release highlights in the release notes, while the changelog contains a list of relevant changes. Not that important though

[p-offtermatt]

One typo, but approval otherwise.

[p-offtermatt]

Regenerate this after fixing summary.md

[MSalopek]

Linter failing is fine, it complains about uintPtr helper function from e2e tests - this is an artifact left over from removing provider throttling v2 changes.

[mpoke]

Update the .changelog/epilogue.md file to only contain the v3.1.0 and v3.0.0 sections followed by
```md
## Previous Versions

[CHANGELOG of previous versions](https://github.com/cosmos/interchain-security/blob/main/CHANGELOG.md)
```

See https://github.com/cosmos/interchain-security/blob/main/RELEASE_PROCESS.md#creating-a-new-release-branch

[MSalopek]

Update the .changelog/epilogue.md file to only contain the v3.1.0 and v3.0.0 sections followed by ```md ## Previous Versions

[CHANGELOG of previous versions](https://github.com/cosmos/interchain-security/blob/main/CHANGELOG.md)

See https://github.com/cosmos/interchain-security/blob/main/RELEASE_PROCESS.md#creating-a-new-release-branch

You mean, we need to have v3.2.0, v3.1.0, v3.0.0 and previous versions?

EDIT:
I just made it contain text below since that's whats in the releasing docs.

[CHANGELOG of previous versions](https://github.com/cosmos/interchain-security/blob/main/CHANGELOG.md)

EDIT 2:
I now see that epilogue.md gets added to the bottom of the CHANGELOG.md, that's why the initial statement works - that was not obvious.

[MSalopek]

Closing in favor of #1476