document the exit codes 82 and 83 that are new in 7.19.0

docs/curl.1

@@ -1556,6 +1556,10 @@ The resource referenced in the URL does not exist
 An unspecified error occurred during the SSH session
 .IP 80
 Failed to shut down the SSL connection
+.IP 82
+Could not load CRL file, missing or wrong format (added in 7.19.0)
+.IP 83
+Issuer check failed (added in 7.19.0)
 .IP XX
 There will appear more error codes here in future releases. The existing ones
 are meant to never change.