Fix naming inconsistency between code and markdown

src/config.hpp

@@ -15,7 +15,7 @@ struct ServerConfig {
 
 struct CommitConfig {
   size_t min_request_id_length = 20; // Minimum length for request_id entropy
-  std::chrono::hours request_id_retention_time{
+  std::chrono::hours request_id_retention_hours{
       24}; // How long to keep request IDs
   size_t request_id_retention_versions =
       100000000; // Min versions to retain request IDs