[FLINK-13105] Add documentation for blink planner's built-in functions

• Type: Sub-task
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.9.1, 1.10.0
• Component/s: Documentation, Table SQL / Planner
• Labels: pull-request-available
• Assignee: Zhenghua Gao
• Reporter: Zhenghua Gao
• Created: 05/Jul/19 01:42
• Updated: 27/Aug/19 04:21
• Resolved: 23/Aug/19 06:30

Description

Blink planner intros some built-in functions which need to be documented.

Issue Links

• links to: GitHub Pull Request #9002