Update the introiduction section to add Flask-Basicauth example

[howiezhao]

This PR adds an example of integrating Flask-Basicauth in the Introduction section of the documentation.

[samuelhwilliams]

Could we perhaps do this as a working example in the examples/ directory and point to that? This snippet implies a few things already exist (app, Post, db) - and it'd be nice to just be able to see a functioning example straight away.

[howiezhao]

Could we perhaps do this as a working example in the examples/ directory and point to that? This snippet implies a few things already exist (app, Post, db) - and it'd be nice to just be able to see a functioning example straight away.

Hi @samuelhwilliams Thank you for your reply. The reason why I did not put it in the examples/ is that I think this example is very simple. Its core code is only the following lines:

class MicroBlogAdminIndexView(AdminIndexView):
    @expose('/')
    @basic_auth.required
    def index(self):
        return super().index()

class MicroBlogModelView(ModelView):
    def is_accessible(self):
        return basic_auth.authenticate()

    def inaccessible_callback(self, name, **kwargs):
        return basic_auth.challenge()

This example is very concise compared to the Flask-Login and Flask-Security examples.

As for the app, Post, db, etc. you mentioned, they have actually been mentioned in the context of this document. So, if the user reads this document completely, I don’t think there will be any gaps, what do you think?

[samuelhwilliams]

I think it's alright to rely on context further up in the readme, but that a snippet of code in the README that worked if grabbed just by itself would generally be a better user experience.

I'll accept this PR in a couple days if you don't want to change it, but if you want to update the code snippet to work in isolation that would be great too 🙏