Enhance the Release Notes by adding dropdown menus

[lisagoodrich]

Please use Sphinx Design for Dropdown menus . This will allow for searches of material hidden within dropdown menus.

Changes will need to be made to the below files:

1. config.py
   add 'sphinx_design' to the "extensions =" section. (note the underscore.)
2. requirements.txt file.
   add 'sphinx-design==0.3.0' with a dash
3. METdataio/.github/workflows/documentation.yml
   add a line after this example line 28 . Make sure it is correctly indented.
   python -m pip install -r docs/requirements.txt

It should look like this:
python -m pip install --upgrade python-dateutil requests sphinx
sphinx-gallery Pillow sphinx_rtd_theme
python -m pip install -r docs/requirements.txt
4. Change python-version: '3.10'
back to python-version: '3.8' in the METcalcpy/.github/workflows/documentation.yml file

The dropdown menus won't work unless this is added.
Panel drop downs would be added for the subcategories and sub-subcategories. For example,
-Repository and build
---Installation
---Static Code Analysis
---Testing
---Continuous Integration
-Documentation
-Library code
---Bugfixes
---Python embedding enhancements
---Miscellaneous
---NetCDF Library
---Statistics computations
etc.

Describe the Task

Provide a description of the task here.

Time Estimate

less than a day

Sub-Issues

None

Relevant Deadlines

NONE.

Funding Source

Split between accounts 2702691 and 2792542.

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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.
• 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.