Proposed schedule for JavaFX 18

[Kevin Rushforth]

Here is the proposed schedule for JavaFX 18.

RDP1: Jan 13, 2022 (aka “feature freeze”)
RDP2: Feb 3, 2022
Freeze: Feb 24, 2022
GA: Mar 15, 2022

We plan to fork a jfx18 stabilization branch at RDP1. The GA date is one 
week ahead of JDK 18, matching what we did for 17.

The start of RDP1, the start of RDP2, and the code freeze will be 16:00 
UTC on the respective dates.

Please let Johan or me know if you have any questions.

-- Kevin