Fixed lint issues and missing documentation

README.md

@@ -121,9 +121,11 @@ Using a source called `example` as an illustration:
    - Define `JobSearchConfigSourceExample`, embedding `JobSearchConfigSource`
      (for `enabled` and `interval`), plus any fields of its own with `cfg` and
      optional `default` tags, e.g. ``APIRoot string `cfg:"api_root"` ``.
-   - Copy the standard `Map`, `Flatten`, `TypeOf`, `ValueOf` and `SetValue`
-     methods, renaming the receiver type and using the new constant in
-     `Flatten`.
+   - Implement the `Section` interface (see `internal/config/section.go`):
+     copy the `Map`, `Flatten`, `TypeOf`, `ValueOf` and `SetValue` methods
+     from an existing source, under a
+     `// ---------- Section methods (see Section) ----------` banner, renaming
+     the receiver type and using the new constant in `Flatten`.
 2. **Register the section:** add
    ``Example JobSearchConfigSourceExample `cfg:"example"` `` to
    `JobSearchConfigSources` in `internal/config/conf_sources.go`. The `cfg` tag
@@ -148,11 +150,12 @@ Using a source called `example` as an illustration:
        start("Example", runExample)
    }
    ```
-6. **Tests:** add tests for the new config section to
-   `internal/config/conf_sections_test.go` (add it to
+6. **Tests:** `TestSections` checks the new section implements `Section`
+   and that its keys match its `cfg` tag, with no changes needed. In
+   `internal/config/conf_sections_test.go`, add the section to
    `TestConcreteSourceSections` and update the key count in
-   `TestSourcesSection`), and for the client and worker, using `httptest`
-   servers rather than the real service.
+   `TestSourcesSection`. Test the client and worker using `httptest` servers
+   rather than the real service.
 7. **Docs:** add the source and its keys to the key table in
    `internal/config/README.md`.