Add badges

[miguelgfierro]

Description

Related Issues

References

Checklist:

• [ ] I have followed the contribution guidelines and code style for this project.
• [ ] I have added tests covering my contributions.
• [ ] I have updated the documentation accordingly.
• [ ] I have signed the commits, e.g. git commit -s -m "your commit message".
• [ ] This PR is being made to staging branch AND NOT TO main branch.

[SimonYansenZhao]

I would suggest the 'slack|join' badge/button be placed under the recommenders logo or be bigger so that people can notice there is a slack channel they can join. @miguelgfierro

[anargyri]

The slack badge is a bit misaligned when I open the front page on my PC. Maybe move it to the next line?

[anargyri]

Now it looks better 👍

[miguelgfierro]

@anargyri the one with slack at the level of Recommenders or this one:

[anargyri]

I think this one is even better

[anargyri]

Another thing: we don't really need the title "Recommenders" if we have the logo that says the same thing, do we? It is a repetition.

[miguelgfierro]

I like it more without Recommenders repeated. Looks nice!

What do you think @SimonYansenZhao?