Add FAQ documentation page

Covers private registries, ecosyste.ms relationship, and the Ruby origins.

Author: andrew

content/docs/_index.md

@@ -16,6 +16,7 @@ git-pkgs tracks your dependency history across git commits. Initialize a databas
   {{< card link="bisect" title="Bisect" subtitle="Binary search for dependency changes" >}}
   {{< card link="diff-driver" title="Diff Driver" subtitle="Readable lockfile diffs" >}}
   {{< card link="managing-packages" title="Managing Packages" subtitle="Install, add, update, remove" >}}
+  {{< card link="faq" title="FAQ" subtitle="Common questions" >}}
 {{< /cards >}}
 
 ### Libraries

content/docs/faq.md

@@ -0,0 +1,29 @@
+---
+title: FAQ
+weight: 60
+---
+
+## Does git-pkgs work with private registries?
+
+For commands that **query registries** (`outdated`, `licenses`, SBOM enrichment):
+
+git-pkgs extracts registry URLs from lockfiles when the format supports it:
+- npm: package-lock.json, yarn.lock, pnpm-lock.yaml, bun.lock
+- pypi: Pipfile.lock, poetry.lock, uv.lock
+- cargo, composer, gem lockfiles
+
+If your lockfile points to a private registry (like Artifactory or GitHub Packages), those URLs are used automatically. However, git-pkgs doesn't currently read config files like `.npmrc` or `.pypirc` for registry URLs or credentials. Authenticated private registries aren't supported yet for registry queries.
+
+For commands that **run package managers** (`install`, `add`, `remove`, `update`):
+
+These delegate to the actual CLI tools, which respect their native config files. Private registries, proxies, and credentials work as you'd expect.
+
+## How is git-pkgs related to ecosyste.ms?
+
+[ecosyste.ms](https://ecosyste.ms) is a set of open APIs for package ecosystem data, created by [Andrew Nesbitt](https://nesbitt.io) (who also created git-pkgs). git-pkgs can query package registries directly, but ecosyste.ms also provides source repository information for each package which often gives a better picture.
+
+You can bypass ecosyste.ms and query registries directly with `git config pkgs.direct true`. This is useful for private registries or airgapped environments.
+
+## Wasn't this originally written in Ruby?
+
+Yes. The [original git-pkgs](https://github.com/andrew/git-pkgs) was a Ruby gem. This Go rewrite ships as a single binary for easier installation and enables future integration with projects like [gittuf](https://gittuf.dev), [sbommit](https://github.com/sbommit), and [Forgejo](https://forgejo.org).