Docs: Fix table styling example having wrong structure

[steffunky]

Suggested merge commit message (convention)

Docs table: Fix table styling example having wrong structure

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Additional information

If you use the current example in the documentation you'll get this error when building:

ERROR in /srv/http/iTop/js/ckeditor/src/ckeditor.ts
219:16-225:17
[tsl] ERROR in /srv/http/iTop/js/ckeditor/src/ckeditor.ts(219,17)
      TS2322: Type '{ defaultProperties: { borderStyle: string; borderColor: string; borderWidth: string; alignment: string; width: string; height: string; }; tableCellProperties: { defaultProperties: { horizontalAlignment: string; verticalAlignment: string; padding: string; }; }; }' is not assignable to type 'TablePropertiesConfig'.
  Object literal may only specify known properties, and 'tableCellProperties' does not exist in type 'TablePropertiesConfig'.
ts-loader-default_e3b0c44298fc1c14

Fixing the example structure allows to build and to set the default table style to CKEditor build