📝 Require concise prose in development/

Actionable sentence in CONTRIBUTING.md § Rules the tools don't enforce;
the why — humans skim, agents imitate the dominant style, so verbosity
compounds — in development/README.md § Decision blocks. Both sides in
one commit per the write-each-fact-once rule.

development/README.md

@@ -66,6 +66,9 @@ of downloading per job.
   goes under a `## Known issues` section at the end of the file.
 - Replace a superseded decision in place rather than archiving it; git history
   is the archive.
+- Terse is the point: humans skim and agents imitate the style already in the
+  file, so verbosity compounds edit over edit. Grammar loses to density here on
+  purpose.
 
 ## Adding to these docs