Update README: document correct password limitation

Clarified that most special characters work fine, including #.
Only combination of spaces AND quotes together causes issues.

README.md

@@ -286,7 +286,11 @@ Use the provided build script:
 - SSL/TLS setting (default: yes)
 
 **⚠️ Password Limitation:**
-The build script uses simple shell variable substitution for credentials. Passwords containing spaces, double quotes (`"`), or dollar signs (`$`) may cause the build to fail. If your password contains these characters, consider using a simpler password or manually editing the build command.
+The build script uses a heredoc approach for credentials. This works for most passwords, including those with special characters like `#` (hash). However, passwords containing **both spaces AND quotes together** (e.g., `"pass word"`) may fail.
+
+If your password contains both spaces and quotes, consider:
+- Using a simpler password
+- Manually editing the build command
 
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