Fix typo in the list of env vars

Author: sosedoff

pkg/command/options.go

@@ -237,7 +237,7 @@ func AvailableEnvVars() string {
 	return strings.Join([]string{
 		"  " + envVarPrefix + "DATABASE_URL  Database connection string",
 		"  " + envVarPrefix + "URL_PREFIX    HTTP server path prefix",
-		"  " + envVarPrefix + "SESSIONS:     Enable multiple database sessions",
+		"  " + envVarPrefix + "SESSIONS      Enable multiple database sessions",
 		"  " + envVarPrefix + "LOCK_SESSION  Lock session to a single database connection",
 		"  " + envVarPrefix + "AUTH_USER     HTTP basic auth username",
 		"  " + envVarPrefix + "AUTH_PASS     HTTP basic auth password",