doc: user_guide: add missing word in Troubleshooting / Restarts

[phil-blain]

PR checklist

• Short (1 sentence) summary of your PR:
  see title
• Developer(s):
  me
• Suggest PR reviewers from list in the column to the right.
• Please copy the PR test results link or provide a summary of testing completed below.
  No tests, only doc change.
• How much do the PR code changes differ from the unmodified code?
  • bit for bit
  • different at roundoff level
  • more substantial
• Does this PR create or have dependencies on Icepack or any other models?
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• Does this PR add any new test cases?
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• Is the documentation being updated? ("Documentation" includes information on the wiki or in the .rst files from doc/source/, which are used to create the online technical docs at https://readthedocs.org/projects/cice-consortium-cice/. A test build of the technical docs will be performed as part of the PR testing.)
  • Yes
  • No, does the documentation need to be updated at a later time?
    • Yes
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• Please provide any additional information or relevant details below:
  I noticed that while reading that section and figured I might as well correct it right away.

[eclare108213]

Good catch. There might be other places in the docs where 'netCDF' is missing -- I think it was a special command in the original LaTeX, which might not have translated to rtf.