[FLINK-20543] Fix typo in upsert kafka docs

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.12.0
• Fix Version/s: 1.12.1, 1.13.0
• Component/s: Documentation, Table SQL / Ecosystem
• Labels: pull-request-available
• Assignee: xiaozilong
• Reporter: xiaozilong
• Created: 09/Dec/20 04:47
• Updated: 09/Dec/20 07:24
• Resolved: 09/Dec/20 07:15

Issue Links

• links to: GitHub Pull Request #14343