Install BestieTemplate.jl in usage instructions

[fdiblen]

Description

If the users do not have BestieTemplate installed on their systems, they first need to install it. I suggest to update the usage instructions (https://abelsiqueira.com/BestieTemplate.jl/stable/#Using)

from

julia> using BestieTemplate
julia> BestieTemplate.generate("YourPackage.jl")

to

julia> import Pkg; Pkg.add("BestieTemplate")
julia> using BestieTemplate
julia> BestieTemplate.generate("YourPackage.jl")

This could be added to the following code snippets as well.

• https://abelsiqueira.com/BestieTemplate.jl/stable/10-full-guide/#new_package
• https://abelsiqueira.com/BestieTemplate.jl/stable/10-full-guide/#existing_package

[abelsiqueira]

The docs file also have the information, but in an earlier section. It is otherwise done in #342.