sequelize instance does not have a Model field (import docs)

[masterl]

Issue Description

The import docs present a wrong code:

module.exports = (sequelize, DataTypes) => {
  class Project extends sequelize.Model { }

What was unclear/insufficient/not covered in the documentation

The problem here is that there is no field called Model on the sequelize instance.

If possible: Provide some suggestion on how we can enhance the docs

Throughout the docs, sequelize is used for the Sequelize instance.
And Sequelize is used for what we get when we require('sequelize').
Since Model is a part of Sequelize (with capital S), this part of the doc should be rewritten to Sequelize.Model.

Additional context

Add any other context or screenshots about the issue here.

Issue Template Checklist

Is this issue dialect-specific?

• No. This issue is relevant to Sequelize as a whole.
• Yes. This issue only applies to the following dialect(s): XXX, YYY, ZZZ
• I don't know.

Would you be willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time and I know how to start.
• Yes, I have the time but I don't know how to start, I would need guidance.
• No, I don't have the time, although I believe I could do it if I had the time...
• No, I don't have the time and I wouldn't even know how to start.

[papb]

Thanks! I will fix this while I'm making the other docs changes.