[aspnetcore] Fix config enum documentation

[hauntingEcho]

To fix #9398

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technical committee mentions: @mandrean @frankyjuang @shibayan @Blackclaws

[wing328]

LGTM

[wing328]

Looks like this change is causing an issue in publishing updated documentation to the public website as part of the Travis CI workflow:

[success] [webpackbar] Client: Compiled with some errors in 2.46m


../docs/generators/aspnetcore.md
SyntaxError: unknown: Expected corresponding JSX closing tag for <strong> (34:82)

  32 | <td parentName="tr" {...{"align":null}}>{`classModifier`}</td>
  33 | <td parentName="tr" {...{"align":null}}>{`Class Modifier for controller classes: Empty string or abstract.`}</td>
> 34 | <td parentName="tr" {...{"align":null}}><dl><dt>{`*`}<strong parentName="td">{`*`}</dt><dd>{`Keep class default with no modifier`}</dd><dt></strong>{`abstract**`}</dt><dd>{`Make class abstract`}</dd></dl></td>
     |                                                                                   ^
  35 | <td parentName="tr" {...{"align":null}}></td>
  36 | </tr>
  37 | <tr parentName="tbody">
 @ ./.docusaurus/registry.js 1:25362-25423 1:25236-25318
 @ ./node_modules/@docusaurus/core/lib/client/exports/ComponentCreator.js
 @ ./.docusaurus/routes.js
 @ ./node_modules/@docusaurus/core/lib/client/clientEntry.js
 @ multi ./node_modules/@docusaurus/core/lib/client/clientEntry.js

ref: https://travis-ci.org/github/OpenAPITools/openapi-generator/builds/771409157

[wing328]

I think it's due empty string "" as the enum value: https://github.com/OpenAPITools/openapi-generator/pull/9404/files#diff-c8d3b05be5059a6612785c8de1e952973400d80ea639375e784e3a7f01beca9bR291. I'll file a PR to revert the change and see if the issue goes away