docs: add LOG_DUMP guide

LOG_DUMP.md

@@ -0,0 +1,23 @@
+# Log Dump Guide
+
+In order to debug some issues, it is useful to supply a log dump of your Mantle command.
+
+> ⚠️ Generating a log dump will include your `ROBLOSECURITY` cookie and potentially your AWS credentials. Make
+> sure to remove all secrets from your log file before sending it to us.
+
+To generate a log dump:
+
+1. Set the `RUST_LOG` environment variable to exactly `trace,cookie_store=error,html5ever=error,selectors=error`.
+   ```sh
+   # PowerShell
+   $env:RUST_LOG="trace,cookie_store=error,html5ever=error,selectors=error"
+   # Bash
+   export RUST_LOG="trace,cookie_store=error,html5ever=error,selectors=error"
+   ```
+2. Re-run your Mantle command with a stderr redirect to a log file.
+   ```sh
+    # PowerShell or Bash
+    mantle deploy 2> out.log
+   ```
+3. Remove all secrets from `out.log`. Search the file for `ROBLOSECURITY` and your `AWS_ACCESS_KEY_ID` (if
+   applicable) and remove all references.