A choice setting's refusal names what it takes, and /commands lists them

Bare Placement and BootShell flip, which is pardes's convention for a word
that chooses (Crt does too), but nothing said so, and "bad value in control
message" never said what would do. A refused value now says `takes acme,
pardes` (every switch and choice setting), /commands lists each such
setting's values in a fourth field, and config.md and fs.md say that bare
steps to the next. Motion and ShaderAnimation stepped nowhere bare and now
step like the rest.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 7 insertions, 1 deletions

diff --git a/docs/config.md b/docs/config.md
index 0332d854..434a1778 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -120,7 +120,13 @@ document in a column of its own. See [where new panes go](tags.md#where-new-pane
 into the left column beside it, whatever it holds; `BootShell replace` closes
 such a shell there when it is the column's only one and nobody has typed
 into it (no scrollback, cursor still on the first prompt line), the boot's
-placeholder giving its rows to the document. Bare `BootShell` flips it.
+placeholder giving its rows to the document. Bare `BootShell` flips it, as
+bare `Placement` does: a setting that chooses among words (`on`/`off`
+switches, `Placement`, `BootShell`, `Crt`, `Lift`, `Motion`,
+`ShaderAnimation`) steps to its
+next value when written bare, as its word clicked in a tag does, and a value
+it does not take is refused with the values it takes, which `/commands` also
+lists.
 `Verbose` toggles the message-row announcement every builtin makes of its own
 name before it runs; it is on by default, and the builtins that own the message
 row themselves (`Msg`) never announce. Turning it off leaves the row to the