openapi: the danglingDir comment says twelve reproducers; there are fourteen

[OmarAlJarrah]

Problem

compilers/openapi/danglingcheck_test.go:25 says:

// danglingDir holds the twelve issue-#14 reproducers, copied out of triage so the tests are self-contained.

There are fourteen, and the test's own table names all fourteen:

$ ls testdata/dangling/openapi/*.yaml | wc -l
14
$ sed -n '/cases := \[\]struct/,/^\t}$/p' compilers/openapi/danglingcheck_test.go | grep -c '^\t\t{"'
14

f31-discriminator-empty-name.yaml and f32-ref-noncanonical-escape.yaml are the two the count
predates. The number was true when written and rotted as fixtures were added, which is the same
failure mode as #299 and the docs/architecture.md package tree.

Expected

Drop the count: "danglingDir holds the issue-#14 reproducers" loses nothing, and the table below
it is the enumeration. A count in a comment beside the list it counts has no way to stay true.

Notes

Noticed while documenting testdata/dangling/ in README. Comment-only; no behaviour change.