docs: Delete roadmap folder from docs.

[jtremback]

Description

Was super outdated, and probably doesn't belong in the docs anyway. I don't know if this is going to break any links and how we should check for that or set up redirects so I am leaving this in draft.

Relevant: #2451

---

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 type prefix in the PR title
• Added ! to the type prefix if API or client breaking change
• Targeted the correct branch (see PR Targeting)
• Provided a link to the relevant issue or specification
• Followed the guidelines for building SDK modules
• Included the necessary unit and integration tests
• Added a changelog entry to CHANGELOG.md
• Included comments for documenting Go code
• Updated the relevant documentation 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 type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage

[MSalopek]

@jtremback @mmulji-ic
Please check this earlier PR, it renames roadmap to release log (which we actually have and can keep in the docs).
#2275

[mmulji-ic]

@jtremback would prefer this #2560

[mmulji-ic]

Closed in favour of approved #2560 , cc @jtremback