Option to customize name in the footer

[cuducos]

Is your feature request related to a problem?

Not a problem, just a new use case. Usually I don't use my (full) name in presentations, I tend to use my social network user handle instead — in my case, @cuducos instead of Eduardo Cuducos.

Describe the solution you'd like

I can open a PR to add a flag to overwrite the user name when used, e.g.:

# slides exmaple.md --name "@cuducos"

This would use @cuducos in the “footer” instead of the full name of the logged user. This logic can be wrapped in cmd/root.cmd using Cobra.

Describe alternatives you've considered

Maybe we could use another naming, such as --footer — what do you think?

[maaslalani]

I proposed a solution to solve both this issue and #87

With #87 (comment)

Something like the following at the top of the slides.

---
theme: foo.json # this is already implemented
author: @cuducos
date: 1970-01-01
---

I think this approach is nicer than having to add CLI flags everytime.

[cuducos]

Awesome! Closes #91