Change "may" to "should" in note that we should audit existing targets

Author: joshtriplett

text/0000-target-tier-policy.md

@@ -725,9 +725,9 @@ downstream users, especially people who may be relying indirectly on a
 non-tier-1 Rust target and who may have expectations that do not match the
 target tier.
 
-Some of our existing targets may not meet all of these criteria today. We may
-audit existing targets against these criteria, but this RFC does not constitute
-a commitment to do so in a timely fashion.
+Some of our existing targets may not meet all of these criteria today. We
+should audit existing targets against these criteria, but this RFC does not
+constitute a commitment to do so in a timely fashion.
 
 In the future, we may have a specified approval body for evaluating legal
 requirements, in consultation with legal professionals.