fix(11.1-07): require built, run src= code; case-sensitive go doc; parse command forms

- .go src= targets must be in the default build and reached from a Test or an Example with output
- go doc -c makes the identifier fallback case-sensitive
- commandWord parses env prefixes, flags, go run and bin/ forms

docs/console/utilities.md

@@ -42,6 +42,6 @@ summer docs:sync
 summer docs:serve
 ```
 
-`docs:build` fails, and writes nothing, when a page names an identifier that does not exist, links to a missing page or anchor, shows a command that neither `summer` nor an application binary has, or has a `src=` code block that differs from its source. It also fails on a Go code block (including `golang`) without a `src=` reference, a `src=` code block inside a callout, blockquote or list item (`src=` blocks must be top-level), and a `src=` code block in a module README. After you change code that a page shows, run `summer docs:sync` to refresh the copies.
+`docs:build` fails, and writes nothing, when a page names an identifier that does not exist, links to a missing page or anchor, shows a command that neither `summer` nor an application binary has, or has a `src=` code block that differs from its source. It also fails on a Go code block (including `golang`) without a `src=` reference, a `src=` code block inside a callout, blockquote or list item (`src=` blocks must be top-level), and a `src=` code block in a module README. A `src=` target must be code `go test ./...` compiles and runs, that is a file in the default build, inside a `Test` function or an `Example` with an `// Output:` comment, or a function one of them calls. After you change code that a page shows, run `summer docs:sync` to refresh the copies.
 
 `docs:serve` listens only on a loopback address unless you pass `--allow-remote`. Use it to preview search, which browsers block when you open the built files directly from disk.