Document unquoted DCO sign-off names

Signed-off-by: Robert Kruszewski <github@robertk.io>

Author: robert3005

AGENTS.md

@@ -230,5 +230,8 @@ ambiguous, ask the user instead of inventing a prefix.
 All commits must be signed off by the committers in this form:
 
 ```text
-Signed-off-by: "COMMITTER" <COMMITTER_EMAIL>
+Signed-off-by: COMMITTER <COMMITTER_EMAIL>
 ```
+
+Do not put quotation marks around the committer's name in the sign-off trailer. The name and
+email must match the commit identity so DCO checks can recognize the sign-off.