Fix delegation info tooltip text

[dcroote]

Fixed: Tooltip text

Implementation details

"validators" should be singular ("validator") to agree with "this"

Please ensure the following requirements are met before submitting a pull request:

• [ ] The pull request is targeted against the correct target branch - unclear, applies to multiple branches?
• [ ] The pull request is linked to an issue with appropriate discussion and an accepted design OR is linked to a spec that describes the work. - N/A
• [x] The pull request includes a description of the implementation/work done in detail.
• [x] The pull request includes any and all appropriate unit/integration tests - None needed
• [ ] You have added a relevant changelog entry to CHANGELOG_UNRELEASED.md - Seems unnecessary, but I can if requested
• [x] You have re-reviewed the files affected by the pull request (e.g. using the Files changed tab in the Github PR explorer)