Easter eggs are more fun when they're hidden

[AshlinHarris]

This pull zeros out motivational_word_probability parameter, which effectively hides the motivational messages by default.

The motivational messages add some levity to the development process and have received positive feedback from the community. On the other hand, at least some developers find them somewhat distracting. The random messages are bold and vivid, which can draw a user's attention unnecessarily. This potential issue can be compounded if the end user is a nondeveloper, since they might not be aware of the context and probably shouldn't be redirected to the Julia discourse home page.

This change would fix #3062

Try this Pull Request!

Open Julia and type:

julia> import Pkg
julia> Pkg.activate(temp=true)
julia> Pkg.add(url="https://github.com/AshlinHarris/Pluto.jl", rev="main")
julia> using Pluto

[fonsp]

Be respectful and positive please!

[fonsp]

https://www.youtube.com/watch?v=o_4EX4dPppA