chore: add AGENTS.md file

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

Author: dvdksn

AGENTS.md

@@ -0,0 +1,75 @@
+# AGENTS.md
+
+Instructions for AI agents working on the Docker documentation
+repository. This site builds https://docs.docker.com/ using Hugo.
+
+## Project structure
+
+```
+content/          # Documentation source (Markdown + Hugo front matter)
+├── manuals/      # Product docs (Engine, Desktop, Hub, etc.)
+├── guides/       # Task-oriented guides
+├── reference/    # API and CLI reference
+└── includes/     # Reusable snippets
+layouts/          # Hugo templates and shortcodes
+data/             # YAML data files (CLI reference, etc.)
+assets/           # CSS (Tailwind v4) and JS (Alpine.js)
+static/           # Images, fonts
+_vendor/          # Vendored Hugo modules (read-only)
+```
+
+The `/manuals` prefix is stripped from published URLs:
+`content/manuals/desktop/` → `/desktop/` on the live site.
+
+## Writing guidelines
+
+Read and follow [STYLE.md](STYLE.md) and [COMPONENTS.md](COMPONENTS.md).
+These contain all style rules, shortcode syntax, and front matter
+requirements.
+
+## Vendored content (do not edit)
+
+Content in `_vendor/` and CLI reference pages generated from
+`data/cli/` are vendored from upstream repos. Don't edit these
+files — changes must go to the source repository:
+
+- docker/cli, docker/buildx, docker/compose, docker/model-runner → CLI reference YAML in `data/cli/`
+- moby/buildkit → Dockerfile reference in `_vendor/`
+- moby/moby → Engine API docs in `_vendor/`
+
+If a validation failure traces back to vendored content, note the
+upstream repo that needs fixing but don't block on it.
+
+## Commands
+
+```sh
+npx prettier --write <file>        # Format before committing
+docker buildx bake validate        # Run all validation checks
+docker buildx bake lint            # Markdown linting only
+docker buildx bake vale            # Style guide checks only
+docker buildx bake test            # HTML and link checking
+```
+
+## Verification loop
+
+1. Make changes
+2. Format with prettier
+3. Run `docker buildx bake lint vale`
+4. Run a full build with `docker buildx bake`
+
+## Self-improvement
+
+After every correction or mistake, update this file with a rule to
+prevent repeating it. End corrections with: "Now update AGENTS.md so
+you don't make that mistake again."
+
+## Mistakes to avoid
+
+- Don't use hedge words: "simply", "easily", "just", "seamlessly"
+- Don't use meta-commentary: "it's worth noting that...", "it's important to understand that..."
+- Don't use "allows you to" or "enables you to" — use "lets you" or rephrase
+- Don't use "we" — use "you" or "Docker"
+- Don't use "click" — use "select"
+- Don't bold product names or for emphasis — only bold UI elements
+- Don't use time-relative language: "currently", "new", "recently", "now"
+- Don't edit vendored content in `_vendor/` or `data/cli/`