nestlog: missed commit log_config.hpp

include/nestlog/log_config.hpp

@@ -0,0 +1,22 @@
+/* @file log_config.hpp */
+
+#pragma once
+
+#include <cstdint>
+
+namespace xo {
+    /* Tag here b/c we want header-only library */
+    template <typename Tag>
+    struct log_config_impl {
+        /* spaces per indent level */
+        static std::uint32_t indent_width;
+    }; /*log_config_impl*/
+
+    template <typename Tag>
+    std::uint32_t
+    log_config_impl<Tag>::indent_width = 1;
+
+    using log_config = log_config_impl<class log_config_tag>;
+} /*namespace xo*/
+
+/* end log_config.hpp */