Give user more control over which collection to work with

[naivej]

I really like qmd and I think the following features can make it easier to use (basically give user more control over collections)

1. Allow adding multiple paths to a collection qmd collection add path1 path2 --name collection_name.
2. Allow excluding certain subfolders from a collection qmd collection add parent --name collection_name -- exclude parent/subfolder. Maybe this can be done using --mask? I'm not sure.
3. Allow re-index and embed selected collection qmd update -c collection, qmd embed -c collection. I think both simply redo all collections and ignore -c
4. Not sure if this is a good idea, but can we have cache files for different collections? I want to sync certain collections across machines, so I don't have run embeding on my slow laptop when I go out.
5. I wish to search / query a subfolder of a collection: qmd query "something" -c collection/subfolder
6. qmd wiki lint should only check wiki collection by default, although I can do so using -c (not documented). Currently wiki lint check everything and report broken links in non-wiki collections.

Minor things

1. qmd ls but qmd context list. Can we use either ls or list.
2. documentation can be improved. For example, where can I use -c.
   • Tips says "Add update commands to keep collections fresh" using `qmd collection update-cmd 'git stash && git pull --rebase --ff-only && git stash pop'. This is also not documented

Please correct me if any of these features are already supported. Thank you!