docs: add mkdocs usage instructions

docs/README.md

@@ -0,0 +1,31 @@
+# Documentation Overview
+
+This directory contains the sources used to generate the **bolt.diy** documentation site.
+It uses [MkDocs](https://www.mkdocs.org/) with the Material theme to build a static site from the files in [`docs/docs`](docs/docs).
+The build configuration lives in [`mkdocs.yml`](mkdocs.yml).
+
+## Building or Serving the Docs
+
+1. Install the documentation dependencies using [Poetry](https://python-poetry.org/):
+
+   ```bash
+   cd docs
+   poetry install
+   ```
+
+2. To preview the documentation locally, run:
+
+   ```bash
+   poetry run mkdocs serve -f mkdocs.yml
+   ```
+
+   This starts a local server and watches for changes.
+
+3. To generate the static site, run:
+
+   ```bash
+   poetry run mkdocs build -f mkdocs.yml
+   ```
+
+   The site will be output to the directory specified by `site_dir` in `mkdocs.yml` (currently `../site`).
+