fix minor spelling mistake in roadmap - #167888

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

autosubmit label was removed for flutter/flutter/167888, because This PR has not met approval requirements for merging. The PR author is not a member of flutter-hackers and needs 1 more review(s) in order to merge this PR.

• Merge guidelines: A PR needs at least one approved review if the author is already part of flutter-hackers or two member reviews if the author is not a flutter-hacker before re-applying the autosubmit label. Reviewers: If you left a comment approving, please use the "approve" review action instead.

auto label is removed for flutter/flutter/167888, Failed to enqueue flutter/flutter/167888 with HTTP 400: GraphQL mutate failed.

auto label is removed for flutter/flutter/167888, Failed to enqueue flutter/flutter/167888 with HTTP 400: GraphQL mutate failed.

auto label is removed for flutter/flutter/167888, Failed to enqueue flutter/flutter/167888 with HTTP 400: GraphQL mutate failed.

This was merged directly to main and must be removed to resume synchronization between master->main. Once done, you can re-open a PR for master.