venues moved to bedrock; keep only the sentence about externals

bedrock publishes venues.md now, so the four-line section here had become the
second saying of a rule owned elsewhere.

Kept the one sentence that is genuinely this document's: put a choice where
reconciliation will look for it, because a .usages.md is what somebody opens when
a document moves.

The old heading — "venues, for things you cannot fetch" — was wrong and had been
since it was written. A venue is not defined by being unfetchable, it is defined
by your having decided something. Kafka's documentation is extremely fetchable.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.loom/published/externals.md

@@ -147,13 +147,16 @@ do; a closed gap is what you needed and got.*
 **The new copy replaces the old pair wholesale.** *There is no merging a document
 you do not own.*
 
-## Venues, for things you cannot fetch
+## A choice about something you adopted does not go in a venue file
 
-**`.loom/venues/<name>.md`** — *Kafka, React, HTTP.* **Choices we made about
-something with no document to hang them on.**
+**Put a choice where reconciliation will look for it.** *When the thing you
+decided about publishes a document you hold a copy of, the choice belongs in the
+`.usages.md` beside that copy* — **because that is the file somebody opens when
+the document moves.**
 
-*If there is a document, hang it there instead: **put a choice where
-reconciliation will look for it.***
+*Venues are for what is left: things that constrain you without publishing
+anything you could adopt.* **See
+[venues](https://git.hypertheory-labs.dev/loom/bedrock/raw/branch/main/.loom/published/venues.md).**
 
 ## Gaps that belong to nobody