REPO_POLICIES: name examples/ in README, correct the lint example's link

As #159 (comment) says.

- `README.md`: Design names `examples/`.
- `prompts/REPO_POLICIES.md`: the sentence linking
  `examples/go-lint-system-libraries.Dockerfile` says the file holds the
  first lines of a lint phase.

Model: opus-5-5

README.md

@@ -175,7 +175,8 @@ share, and evolve prompts across projects.
 The repository is a collection of Markdown files organized in the `prompts/`
 subdirectory. Each file contains one or more related prompts or policy
 documents. There is no build step or runtime component; the prompts are consumed
-by copying them into other projects or referencing them directly.
+by copying them into other projects or referencing them directly. `examples/`
+holds the example `Dockerfile` files that `prompts/REPO_POLICIES.md` links to.
 
 ## Template Repos
 

prompts/REPO_POLICIES.md

@@ -460,8 +460,8 @@ Key points:
   where alpine says `vips-dev`), and delete the package lists in the same `RUN`,
   so the layer does not keep them. The test phase, on the Debian Go image,
   installs the libraries its tests need the same way. Either install goes right
-  after `FROM`, above `ARG CACHEBUST`. A lint phase that installs system
-  libraries is at
+  after `FROM`, above `ARG CACHEBUST`. The first lines of a lint phase that
+  installs system libraries are at
   `https://git.eeqj.de/sneak/prompts/raw/branch/main/examples/go-lint-system-libraries.Dockerfile`.
 
 ## Python `test` phase