Add documentation links and helpful descriptions to error messages

[0x2b3bfa0]

p1

The following have recently been documented in https://cml.dev/doc, but should also have better CLI errors pointing to said docs:

• [ ] #888
  • https://cml.dev/doc/ref/send-comment#GitHub
• [ ] #880
  • uses: actions/checkout@v3, with.ref: ${{ github.event.pull_request.head.sha }}
  • https://cml.dev/doc/usage?tab=GitHub
• [ ] #941
  • use default GITHUB_TOKEN or GitHub App token, not Personal Access Token
  • https://cml.dev/doc/ref/send-github-check
• [ ] #595
  • [ ] Resource not accessible by integration
  • [ ] Error: Forbidden
    • "Ensure permissions are granted as per https://cml.dev/doc/self-hosted-runners?tab=GitLab#personal-access-token"?
• [ ] #911 (?)
• [x] #628
• [x] #563
• [x] #472
• [x] #813
• [x] #816
• [x] #835

p2

• [ ] #581/r656156462: links like https://err[or].cml.dev/YpQ on errors that are especially tricky to explain inline or require additional context [...] e.g. https://error.dvc.org/no-dvc-cache
• [x] #1222 cml CMD --help links to https://cml.dev/doc/ref/CMD

See also

• #595/862336393: See #563 and #563/r640709086 for a good compromise between error message integrity and end user helpfulness.

try {
  operation();
} catch (error) {
  if (error.message === 'Obscure error')
    error.message += ', please try toggling the "more magic" switch';
  throw error;
}

[0x2b3bfa0]

Linking to #628, #595, #563 and #472 for future references.

[casperdcl]

Also

super minor: maybe newline instead of ', '

[casperdcl]

Now that we have https://github.com/iterative/cml.dev/pull/112, can we also add a https://cml.dev/doc/ref/subcommand link to all subcommand --help output like DVC does? #1222

Meanwhile error messages can link to subsections of the command reference for elucidation.