rename another top level fields file

src/main.zig

@@ -1,7 +1,7 @@
 const std = @import("std");
 const zig_builtin = @import("builtin");
 const build_options = @import("build_options");
-const Config = @import("./config.zig");
+const Config = @import("./Config.zig");
 const DocumentStore = @import("./DocumentStore.zig");
 const readRequestHeader = @import("./header.zig").readRequestHeader;
 const requests = @import("./requests.zig");