corrects explnation of default max_lifetime values in README.md

Author: oakgary

README.md

@@ -992,7 +992,7 @@ const sql = postgres('postgres://username:password@host:port/database', {
 })
 ```
 
-Note that `max_lifetime = 60 * (30 + Math.random() * 30)` by default. This resolves to an interval between 45 and 90 minutes to optimize for the benefits of prepared statements **and** working nicely with Linux's OOM killer.
+Note that `max_lifetime = 60 * (30 + Math.random() * 30)` by default. This resolves to an interval between 30 and 60 minutes to optimize for the benefits of prepared statements **and** working nicely with Linux's OOM killer.
 
 ### Dynamic passwords