docs(terminal-rendering): fix stale send_message fmtArgsGeneric example

mcp__matrix__send_message now has a specific fmtToolUse case and no
longer falls through to fmtArgsGeneric. Update the prose to reflect
that common tools have specific cases.

docs/terminal-rendering.md

@@ -153,8 +153,9 @@ isn't in the built-in `fmtToolUse` switch:
 - multi-field → first 4 pairs trimmed to `k: "v"` /
   `k: [N]` / `k: {…}` with a `…+N` overflow
 
-This keeps `mcp__matrix__send_message` and similar from
-dumping raw JSON.
+This keeps less-frequent tools that don't have a specific
+`fmtToolUse` case from dumping raw JSON. Common matrix and
+hyperhive tools have their own cases and skip this path.
 
 ## Inline ask-operator answer