settings: add auto-generated warning msg for editing the file manually

Hopefully, refraining users from modifying the file unless they are
certain about the potential consequences.

Co-authored-by: Ryan Ofsky <ryan@ofsky.org>

src/common/settings.cpp

@@ -4,6 +4,10 @@
 
 #include <common/settings.h>
 
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
 #include <tinyformat.h>
 #include <univalue.h>
 #include <util/fs.h>
@@ -116,6 +120,13 @@ bool WriteSettings(const fs::path& path,
     std::vector<std::string>& errors)
 {
     SettingsValue out(SettingsValue::VOBJ);
+    // Add auto-generated warning comment only if it does not exist
+    if (!values.contains("_warning_")) {
+        out.pushKV("_warning_", strprintf("This file is automatically generated and updated by %s. Please do not edit this file while the node "
+                                          "is running, as any changes might be ignored or overwritten.",
+                                          PACKAGE_NAME));
+    }
+    // Push settings values
     for (const auto& value : values) {
         out.pushKVEnd(value.first, value.second);
     }