Docs improved

[LaysDragon]

now the docs is still broken and need more info .

• godocs friendly comment and example code
• improved generated code templated
  • add comments to missing comment func
  • remain the multi lines in openapi definition
  • add comments to enum
  • improved the enum naming
• docs for gin validator handler
• better field comments and docs
• docs for return data binding helper
• docs for generated order html usage with ecpay
• add comments to these missing comments func