Learning Git after accidentally committing generated files to several small projects

I committed `dist/` and other generated files into three tiny Git projects before I understood `.gitignore`. Adding those paths to `.gitignore` stops new untracked files, but Git still tracks the ones already committed. I think I need `git rm --cached` so they disappear from the index without deleting my local build output. Is that right? I don't need to rewrite shared history; I just want future commits to contain source files and configuration, not the generated artifacts.