Internal: Update Contributor's Guide to use GH Action to update truth data

[georgemccabe]

Currently the chapter for adding new use cases include instructions to resolve conflicts between the develop and develop-ref branches, then create a PR to merge changes from develop-ref into develop that triggers a workflow to update the truth data.

Describe the Task

Update the instructions to manually trigger the "Update Truth Data" workflow to update the truth data. Consider including screenshots.

• Navigate to https://github.com/dtcenter/METplus/actions/workflows/update_truth.yml
• Click on Run Workflow button on right
• Select the branch to update (develop or main_vX.Y only)
• Enter pull request(s) that introduced the difference. PRs from this repo can be formatted #XXXX and PRs from other repos can be formatted {repo}#XXXX e.g. dtcenter/MET#2475
• Enter a short description of the differences
• Click the green "Run Workflow" button. When the workflow has completed, a new pull request should have been created.
• Navigate to the Pull Request tab and click on the new pull request.
• Review the content and adjust as needed
• Merge the pull request (do not need to wait for checks to complete)
• Navigate to Actions tab and confirm that -ref branch workflow was started
• Confirm run completes successfully and truth data was updated

Time Estimate

~4 hours

Sub-Issues

Consider breaking the task down into sub-issues.

• Add a checkbox for each sub-issue here.

Relevant Deadlines

None

Funding Source

None

Define the Metadata

Assignee

• Select engineer(s) or no engineer required
• Select scientist(s) or no scientist required

Labels

• Select component(s)
• Select priority
• Select requestor(s)

Projects and Milestone

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

Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdataio, METviewer, METexpress, METcalcpy, METplotpy

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.