docs: stop implying matrix/bash/forge is a closed todo-producer list

hive-agent-mcp/src/mcp/render.rs

@@ -139,7 +139,8 @@ fn msg_id_tag(id: i64) -> String {
 /// Hard cap on how many individual `Todo` lines `render_loose_ends` will
 /// emit. Approvals/questions/reminders stay naturally bounded (they're
 /// triaged interactively and don't self-multiply), but todos are pushed by
-/// unattended producers (matrix/bash/forge) — an agent that goes a long
+/// unattended producers — matrix/bash/forge are the built-in ones, but any
+/// user-configured MCP server can push its own too — an agent that goes a long
 /// stretch without calling `get_loose_ends`, or whose producers outpace its
 /// triage, can accumulate hundreds of them. Rendering all of them
 /// unconditionally risks producing a tool result too large for the MCP