Bugfix main_v5.0 Fix broken documentation links

[georgemccabe]

Rename configuration RST file back to systemconfiguration to prevent broken links in config files.
Also added sub-heading for info about instances names in the process list so we can link to that info from the tutorial.

Check that table of contents [+] icons are working properly: https://metplus.readthedocs.io/en/bugfix_main_v5.0_doc_links/Users_Guide/systemconfiguration.html

Pull Request Testing

• Describe testing already performed for these changes:
  

Confirmed documentation built successfully and links in config files will not be broken.

Tested using a link from a config file but replacing latest with bugfix_main_v5.0_doc_links:
https://metplus.readthedocs.io/en/bugfix_main_v5.0_doc_links/Users_Guide/systemconfiguration.html#process-list

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  

Check that above link works properly and optionally test other links from config files by replacing latest with bugfix_main_v5.0_doc_links in the URL.

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [Yes]

• Do these changes include sufficient testing updates? [Yes]

• Will this PR result in changes to the test suite? [No]
  

• Please complete this pull request review by 1/5/2023.
  

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[lisagoodrich]

The subsection is correct and follows the documentation standard.

I clicked on the Table of Contents and it's going to the correct area. I tested all of the subsections in chapter 5 and some of the other chapters for good measure.

BUT it's still missing the "+" to open up the Table of Contents further.

[lisagoodrich]

The table of contents [+] icons are working properly. I approve this request.