design: clarify CoC point about unconstructive criticism

Update golang/go#13073

Change-Id: Icb07fc49c854342569599e4bb723ade55593d8c9
Reviewed-on: https://go-review.googlesource.com/17018
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/design/13073-code-of-conduct.md b/design/13073-code-of-conduct.md
index 4e9a0b2..2deb3fa 100644
--- a/design/13073-code-of-conduct.md
+++ b/design/13073-code-of-conduct.md
@@ -105,7 +105,7 @@
    * Derailing: stay on topic; if you want to talk about something else,
      start a new conversation.
    * Unconstructive criticism: don't merely decry the current state of affairs;
-     offer suggestions as to how things may be improved.
+     offer—or at least solicit—suggestions as to how things may be improved.
    * Snarking (pithy, unproductive, sniping comments)
    * Discussing potentially offensive or sensitive issues;
      this all too often leads to unnecessary conflict.