Documentation: Add the METplus development timeline for the next official release to the User's Guide

Describe the Task

This suggestion arose during the NOAA METplus Telecon on April 1, 2024. The development timeline for the next official coordinated release is specified in the settings of the corresponding GitHub project. For example, in the METplus-Wrappers-6.0.0 Development project, the cycle setting defines the target dates for future releases. While the project iteself is public, the settings (including the cycles) are only visible to those with write access, namely those on the METplus Team in the DTCenter GitHub org.

This issue is a documentation task to update the METplus Release Information chapter to list out the planned development timeline.

Recommend only putting this in one spot though because anytime we change our schedule, we'll need to update it...

In this METplus documentation.
In the cycle settings of the METplus, MET, and METplus-Analysis project boards.

Also update the Release Guide for METplus Wrappers to handle this update.

Recommend the following...

Development toward the METplus 6.0.0 Coordinated Release is ongoing and is broken down into the following development release cycles for each component:

Beta1 releases for the METplus components occurred around 2023-09-15.
Beta2 releases for the METplus components occurred around 2023-11-14.
Beta3 releases for the METplus components occurred around 2024-02-08.
Beta4 is tentatively scheduled for 2024-04-10.
Beta5 is tentatively scheduled for 2024-06-05.
Release Candidate 1 has not yet been scheduled.
Official Release has not yet been scheduled.

Update the development release instructions... and remove this content when creating the official release.

Time Estimate

1 hour.

Sub-Issues

Consider breaking the task down into sub-issues.

Relevant Deadlines

List relevant project deadlines here or state NONE.

Funding Source

Define the source of funding and account keys here or state NONE.

Define the Metadata

Assignee

[x] Select engineer(s) or no engineer required
[ ] Select scientist(s) or no scientist required

Labels

[x] Select component(s)
[x] Select priority
[x] Select requestor(s)

Projects and Milestone

[x] Select Repository and/or Organization level Project(s) or add alert: NEED CYCLE ASSIGNMENT label
[x] Select Milestone as the next official version or Future Versions

Define Related Issue(s)

Consider the impact to the other METplus components.

[x] METplus, MET, METdataio, METviewer, METexpress, METcalcpy, METplotpy None needed.

Task Checklist

See the METplus Workflow for details.

[ ] Complete the issue definition above, including the Time Estimate and Funding Source.
[ ] Fork this repository or create a branch of develop. Branch name: feature_<Issue Number>_<Description>
[ ] Complete the development and test your changes.
[ ] Add/update log messages for easier debugging.
[ ] Add/update unit tests.
[ ] Add/update documentation.
[ ] Add any new Python packages to the METplus Components Python Requirements table.
[ ] Push local changes to GitHub.
[ ] Submit a pull request to merge into develop. Pull request: feature <Issue Number> <Description>
[ ] Define the pull request metadata, as permissions allow. Select: Reviewer(s) and Development issues Select: Repository level development cycle Project for the next official release Select: Milestone as the next official version
[ ] Iterate until the reviewer(s) accept and merge your changes.
[ ] Delete your fork or branch.
[ ] Close this issue.

dtcenter / METplus