[suggestion] juliaup add <channel> <version>

[deoradh]

Say I want to peg a channel named dev to the latest 1.7~aarch64 version. With the existing add and link, I don't see that as possible. Consider adding juliaup add <channel> <version>:

• juliaup add dev 1.7~aarch64
  -- downloads version 1.7~aarch64 if needed
  -- adds an entry for dev pointing to 1.7~aarch64

• juliaup add prod lts
  -- downloads version lts if needed
  -- adds an entry for prod pointing to lts

[simeonschaub]

You can do this with juliaup link dev julialauncher +1.7~aarch64

[deoradh]

I thought that required a pointer to the actual julia install path. If that's not the case, then bonus, and maybe this is a docs opportunity.