Add missing C++ constraint docs

[jonaslagoni]

Reason/Context

In the other languages, we have explicit documentation explaining the constraint rules such as for TypeScript: https://modelina.org/docs/constraints/typescript

However, we are missing one for C++.

TODO:

• Go over the constraint logic for C++ for constants: https://github.com/asyncapi/modelina/blob/master/src/generators/cplusplus/constrainer/ConstantConstrainer.ts
• Go over the constraint logic for C++ for enum value and key constraints: https://github.com/asyncapi/modelina/blob/master/src/generators/cplusplus/constrainer/EnumConstrainer.ts
• Go over the constraint logic for C++ for model naming constraints: https://github.com/asyncapi/modelina/blob/master/src/generators/cplusplus/constrainer/ModelNameConstrainer.ts
• Go over the constraint logic for C++ for property key constraints: https://github.com/asyncapi/modelina/blob/master/src/generators/cplusplus/constrainer/PropertyKeyConstrainer.ts

You could potentially copy-paste the TypeScript one: https://github.com/asyncapi/modelina/blob/master/docs/constraints/TypeScript.md and adapt it to C++

[ankur0904]

I want to work on this issue :)

[asyncapi-bot]

🎉 This issue has been resolved in version 3.0.0-next.11 🎉

The release is available on:

• npm package (@next dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[asyncapi-bot]

🎉 This issue has been resolved in version 2.1.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀