Possible generalisation of gitignore targets.

[Skenvy]

trafficstars

Howdy PkgTemplates,

Only started learning julia a few hours ago, so apologies for not being able to quickly parse this repo to find a particularly clear example of what I'm looking to suggest an improvement for ~ but I noticed while following the pkg instructions for setting up on the julia docs page, with a gitignore copied from https://github.com/github/gitignore/blob/main/Julia.gitignore that the ignore targets which contain / don't correctly match subdirectory packages. As an example of what I mean, I've put this PR up on the gitignore repo to fix the issue I was having https://github.com/github/gitignore/pull/4018/files ~ which lets it ignore those globs at any depth -- and was directed here as the likely source of how pkgs are usually managed/created, so wanted to check if this was something that might also be relevant to this repo?

I imagine if some project is managed entirely through this tool, then it would be less relevant, so it might be entirely useless from the perspective of this tool to include a similar change where ever it would apply in here, but just checking for the sake of completeness, although the only example that could have this change applied that I can find in the code is the gitignore(::Documenter) = ["/docs/build/"] in ~/src/plugins/documenter.jl

I do see a debate in an earlier issue about manifest ignore targets, which differs from the suggested default in the currect https://github.com/github/gitignore/blob/main/Julia.gitignore as well, which was committed by a "julia language developer" ~ so I'm not sure how necessary it is to try to keep parity between the gitignore generated by this and that on the github/gitignore repo.